The Bt-2 is roughly similar to the BT-7, except that it only sees tanks of tiers 1-3 instead of 2-5. It is much easier to pwn in as a boss of the battlefield than the BT-7 which is really just a scout most of the time. If there's a tank you should skip it's the A-20. It's not fun as a scout, teh gun is horrible, and it takes 11500 xp to research the T-34, which is FAR superior in every way except absolute speed.
EDIT: Just upgraded my T-34 to historical 1941 standard, but it's very challenging to play with only 86mm of penetration. I can go by the tanks on Prokhorovka and think "I have that exact same one" though.