I like the BTR as a replacement of the Soviet Ranger, though I think it feels a bit more tanky when being shot at by the Allied Tanks. Its mobility and firepower feels right in the middle between the Ranger and APC.
I think the BTR should be made slightly more vulnerable to tank shells and rockets while maintaining its resistance to small arms fire. Its AP/HP is currently 250/250, which shares the same numeric value as the APC (despite having different armor types), but I'd consider lowering its health to 200/200 or 225/225. Its speed and mobility don't need to be changed if you ask me.