I myself don't notice a difference between 40 constant and 60 constant... and 32fps in a rts works great.
For example C&C 3s sage game engine is locked to 32 fps, compare it to SupCom which has no lock. Its hard to tell when zoomed up but when you zoom in closely I think its quite obvious SupCom looks silky smooth ( at least at the start of the game ) while C&C 3 just looks "nice"