just remember that FPS is not everything. I shoot a stock TM which is around 220fps on .25g BB's I have taken out many a people shooting stuff over 300.
Also one thing that will increase your accuracy is the weight of your BB. I think BBB makes a .28 which alot of people seem to be finding the perfect blend of distance, punching power, and accuracy.
Unlike paintball a bush will not provide you with cover in air soft. I used to play paintball and you could hide behind a bloody twig and watch paint break before it hit you. In air soft I have mowed down a bush to get to someone lol. *well not the entire bush but you get my point*
I have shot MT and MB BBs. I personaly see no difference in my Stock TM, prob cause its stock... so I shoot Madbull now as they are cheaper. Metal tech seems to be the most expensive out there.