Yes, you're right, they are straight flyers. Tipplers were originally bred for competition flying. The name of the game is who's birds can stay up the longest. The catch is they must be seen at least once an hour or they are DQ. Because of this they stay very close to the loft. and will fly relatively tight circles. Not as whippy as the flights, but casual swings in either direction. They can also hit the "pins" which is the point in the sky where you can see them but can't actually see them flap their wings. The next step up is disappearing which is what high flyers will do not tipplers as some ignorantly call them "high flying tipplers". People (not us) still compete but that is all but done away with. Mostly they are just "backyard birds" and flown in large flocks or stocks. In competition they fly no more than 7 birds allowed however most fly just 3. In New York you can catch them in the hundreds.
Here is a video of some of ours from a little while back.
Here is a video link to a buddy in Florida's Tipplers. Give it a minute as the birds start off in the pins.
Flights like the Tipplers fly straight, however unlike the Tipplers these have always been a backyard bird and will not fly as long as the Tips do. You can still expect a couple hours in good weather. I've heard of flyers getting 10 our of them. Flights make tighter circles and fly in a tornado pattern with birds (depending upon stock size) sometimes a hundred plus feet lower. They will also "roll out" which means they will leave their loft and travel a couple to 5 miles making circles the whole way gathering up other birds or small stocks in the process. This is a game played in NY call 'Catch keep'
Most agree due to flying style flights are better than Tipplers at this however many fly mixed stocks and some just Tipplers.
We have not been working long with flights and have been flying the young with our Tips so their flying style has been the same so far. Will be splitting them up soon enough.
Flights are also known for being the best "pumpers" which are birds used to feed other birds. The show guys use them to feed their birds which can't feed their own young like short face Budapest and such. They are not flighty at all either and will guard their nest hardcore. With out Tipplers we have found mixed results in the breeding loft. Some will fight you some will be calm and let you see the young with them next to you, other will leave the nest as soon as we enter. Most do okay though.
Here are some flights. (video is not mine)
For some reason can't get a second video to work here is the linke:
It's hard to youtube for New York Flying flights and not get a bunch of airline crap if you don't know who to look at so here is another:
As far as the kit box cost. around $500 or so. Spent $40 on screws and $60 on screen however the screen will do my next two and the screws may finish another. The roofing was also $50 if I remember correctly and will finish the next two as well.
I don't know much about Oriental Rollers however what do you mean by training them? They should not require anything diffrent than any other flying breed.
BTW I have 24 Flights for sale in the other poulty section here.