[Nemo]

Our team has built 4 wheel omni drives like OP is describing on several occasions, and our experience is that they drive pretty nicely without encoder feedback. Maybe the 3 wheel version is touchier.

Encoders could solve the problem described by the OP. Setting the motors to brake instead of coast can solve it faster and cheaper. Adding encoders has additional benefits such as making the robot drive in a straight line and enabling more accurate autonomous driving.

I like instrument feedback. I just don't think it's worth $200 in this case.