You might have it running in "Exact Stop" mode (G61), rather than "Constant Velocity" (G64). A circle is typically done with a G2 or G3 command, which doesn't have any intermediate stopping places, while an elipse is made up of short sections. Try inserting a G64 early in the program, and see if that helps.
If the Techno motors don't need more than 3.5 amps or 50v, the G-540 should work fine. But your controller's probably okay; you just need to get used to the way it works.