Pretty much all chickens were games for the first millenia through the 1800s or so when chicken fancy really caught on, so all breeds eventually can be traced to games. I've dealt with a few game birds, but I haven't been all that amazed, they're usually nice enough with people and make for very alert parents and great broodies, but they're not functional for my needs. I love that  some of them even live to fifteen--let alone are still producing at that age. How cool! 
The games in my area are universally horribly treated though. Even when they're not being used in illegal fighting, they're being allowed to roam pretty much feral throughout the urban neighborhood, kept in tiny cages, or given a couple feet of wire and staked in a yard with no shelter. Beat up game cocks sometimes wander in my yard and beat themselves bloody trying to get in with my birds. Sometimes they even attack me. Can't say I've enjoyed dealing with them, but I'm sure these are terrible specimens.
The Sumatra line I dealt with were surprisingly docile with people, good layers and didn't fight anywhere near as much as I'd thought they would. If I could he down to a single breed again, I might go with the Sumatra from that line (if I could get a hold of some). While a lot of people really like that tail carriage, I don't care for it because it looks ratty and awful as soon as it rains. Sumatra do make for lovely half breeds universally though. 
I know spurless roosters exist and would love to get one, but I've never seen one and don't know of anyone who keeps them. Very neat feature but not something every day, by any stretch. Besides looking cool, multiple spurs don't seem to get as long or pointy, which is part of why I like that trait. I just haven't gotten a hold of either type yet. My Welsummers never successfully hatched any chicks with that spurred hen trait, but it's a wishlist thing to get into a breed for me. They weren't more aggressive and laid wonderfully, so I don't know of any reason to avoid that trait. 
I haven't heard of other breeds besides Sumatra that reliably have the multi-spur trait. I'm sure other birds exist with said trait, but I've never heard of them. As there doesn't seem to be a great reason for avoiding that trait, and it looks pretty cool, I can't see why someone wouldn't try to fix it into some other line or breed. 
I'm not working with mutts and birds of low quality because I want to; I'm working with these birds because they're what I have. Finances, space, time and marital relations all place enormous strain on the project. I can learn about the genetics at least as well with my handful of cheap, poor quality birds as anyone can with expensive birds, and as the learning process is the real point to this project, I don't see any need to acquire expensive or even high quality stock. Yes, realizing the dream of a better bird might take less time with better birds (especially ones with better understood alleles), but there's just as much to be learned this way and the start up is free because I already have everything I need. No one doubts that building a better bird is easier when breeding better birds (at least, it generally works that way) but better birds (certainly the *best* birds) are not always available or within a budget. The cost outweighs the benefit in that scenario. I'm on the bunny course and getting my genetics feet under me still. There are some things which simply must be learned through experience, and I think I'm at the point where I need to supplement my research with actual breeding experience and selecting for traits that I believe will make a chicken which is interesting, productive and suited for this so-called "temperate" climate (aka both heat- and cold-tolerant). 
Yes, domestic animals are adaptable creatures but only an idiot keeps his three-pound Chihuahua as an outside dog in the Great White North. Some animals have been bred to be especially well suited for specific climates. I count it a great success that any Mediterranean breeds can make it at all in Indiana--let alone places which are colder yet than here--but let's not forget how many generations that breed has been here in the States, how rigorously both breeders and birds have been breeding that glorious feature into them (and generally abusing, neglecting, and taking that bird for granted, too). Other Mediterranean breeds have not fared as well in harsher climates, but the Leghorn's history as a landrace and it's battery of dedicated breeders certainly didn't adversely affect that adaptability. 
I have seen small single combs that still got frostbite. The weather here isn't just really cold or really hot--it rapidly shifts between extremes, and that wreaks havoc with everything here. We can go from 75 and sunny to a foot of snow overnight, and back to 55 almost as fast. In other words, there's a lot of melting and freezing going on, and that's what tends to lead to frostbite. The water falling from melting icicles one day would be relatively harmless if the weather staid fairly warm, but this is the Midwest, and Mother Nature is moody here, so that harmless drip is probably going to freeze again in short order. And melt. And freeze. I've yet to see a big, pretty five-pointer on a bird more than two years old here--certainly not for birds which are allowed outside.
 I also can't guarantee a bird is going to have brain one because it tends to be the super-alert, wily guys with the giant single combs who just *have* to roost in trees during snowstorms. Good free ranging, flock protecting instincts always seem to come with the idiocy of roosting in trees during inclement weather. Rain, snow, sleet, hurricanes, tornadoes--won't matter to them. He'll be up a tree like Lieutenant Dan, crowing with all his might, "YOU CALL THIS A STORM?! AHAHAHA!" 
Yes, proper care of a bird can significantly reduce or eliminate the risk of frostbite, but I'm not going to breed a bird and assume that everyone I sell a chick to will provide the absolute best care for said bird. I want a bird that can thrive anywhere it's housed. I won't call it my super bird til I know it's a tank and can take anything. I want to make a bird that can thrive in appalling conditions even because I've seen people treat their chickens like that. I've even seen more neglected birds than pampered birds because to most poultry keepers, chickens are not expensive enough to treat well. Foremost, I want a healthy bird. All other features are extraneous. However, as some traits tend to go along with lessened health and fitness, said traits are not preferred to traits which do not adversely affect a bird's health. 
As single combs are recessive, I expect that they'll be popping up for eons, even if I cull all single combed birds right now. I'm going to see how this crop of birds handle this winter and select my spring breeders from that point. While it's possible that birds with single combs may make that cut, they're not likely to *outperform* other comb types when it comes to the cold (even if they will outperform a male homozygous rose comb for fertility). If I were in a place with a warmer and/or drier winter, I'd go for fancy five-pointers in a heartbeat. 
***I've worked in animal control, live in a crappy neighborhood which is seemingly full of cockfighters, and am an aspiring veterinarian, so I've probably seen some things, and such experience is bound to give me a different perspective. I've never been to chicken show, and I've never actually met someone who raises exhibition fowl.