I think that engineers should be the default vehicle user class, because you can repair, i hate how people in mostly BF3 view vehicles as a disposable transport, especially say transport helicopters or tanks, but then you have the cool helpful people that are your gunner and they ARE an engineer and repair for you. Those small moments of helpfulness make the community seem better than a bunch of 12 year old american noobs.
I think maybe anti-tank grenades would be a good way for all infantry to be a tiny bit useful against tanks. Wouldn't make you overpowered, would just make a tank be cautious before engaging a group of infantry.
http://www.planetside-universe.com/s...d.php?p=694931
Anti-tank grenade thread to see what it would be like.