Hello!
While my main breed of focus is the modern game bantam, I also raise a handful of old English bantams as well!
I’ve found they are very compatible with other breeds. The hens get along with the moderns, and the few large fowl I have just fine and aren’t immediately kicked to the bottom of the pecking order. The roosters, however, in my experience, are usually picked on by my other boys. I only have roosters in my bantams breeds, and the moderns are known to get along, but as soon as I introduced the OEGB Roos, they were suddenly very mean and protective over the hens. They’ve now settled this out, and the two English boys are always together, and just steer clear of the moderns.
In general, my English hens are super talkative, especially when they are hungry or want let outside. They are also incredibly friendly, and affectionate (keep in mind this depends on the bird, but the breed, in general, is very affectionate). Handling of the bird will also affect this, the more you handle them/are around them, the more willing they are to be around you.
I've never let my bantams go sit on their own eggs, I always incubate, or use a broody mom of the cochin or wyandotte bantam breed. I used to have some Large Fowl old English hens, and they were always incredibly broody, and great mothers, but I'm not sure if the bantams have that same broodiness.
The best way to tell about the quality of your bird is to look at the standards. I have both the ABA and APA standard books, and they describe the ideal characteristics of your bird.
According to said standard, she should have a red face/comb/wattle, a dark beak/eyes, and bluish-black legs/toes. The main thing about coloring is that she should be an even shade of slaty blue over her entire feathering.
If you want an extra opinion, it might be a good idea to share a picture of your little gal, I'd sure love to see her! I am in love with the self blue coloring. Plus, the only difference between the self blue and other varieties is feather coloring, leg/beak/face/eye coloring. The type, station, and build of the bird should be the same across the oegb board.
Hope this helps some!
Thanks for your perspective and information!
So far, Gracie my one-and-only OEGB has just finished day three of faithfully sitting on her eggs (
and screeching at any other hen that comes close 
), and seems to be completely dedicated to hatching; I've only seen her off the eggs once since she started sitting, and that was only for 20 minutes while another hen stole her specific nesting box (lol) to lay an egg! (
I took the freshly laid egg, four is enough for both me and my girl, haha).
Afterwards, she went right back onto the eggs.
I just can't believe that only after roughly a month since she first started laying eggs, she's already gone broody!
We didn't actually plan on getting/having more chickens anytime soon, we're happy with the number we have [
8] , but since Gracie went crazy broody and seems so absolutely committed/dedicated to the eggs she has, we decided we'd just feel too bad about taking the eggs and depriving her of the chance at motherhood to break her broodiness; we have more than enough space to tolerate a few more, especially bantams, so we're just going to let what happens, happens

. We ARE limiting her to four eggs though, lol!
My OEGB girl gets along just fine with the flock, even with the much bigger girls, even though we have a large variety of breeds (
Orpington, Barred Rock, Cream Legbar, Polish, Frizzled Cochin bantam x2, Japanese bantam [cockerel], Gracie herself the OEGB).
Considering the fact that we had to integrate the younger ones with the older girls (
Our first chickens were the Orp, BR, CL), they all get along surprisingly well now, especially since we built a whole new huge coop and run for them all; we also let them free range for an hour or two near the end of the day

.
My Self-Blue OEGB conforms to the standard
EXCEPT one odd thing I noticed- on one of her feet, the middle toe-nail is
white instead of
black! How weird, huh?
I think she's absolutely beautiful despite this strange "flaw" though

.
I'll try posting pics or video soon of her and all the girls, personally I think my OEGB is the cutest of the bunch, so tiny and pretty and all that; she's definitely the friendliest, she hops onto my lap and arm without any prompting, and isn't skittish in the slightest

.
It's seriously hilarious to watch her darting around and under the bigger girls with hyper-speed to get at the treats I throw on the ground

.
PS: I think the Modern Game bantams may be on my top 3 list of cutest breeds ever, their legs are just so crazy long! I've seen videos of them pecking around in a yard, I'd die to have a few of them!