Yep, you'll get a higher framerate. The difference in framerates between the (U) and (E) versions is very noticable. The only loss with (U) versions is that they often lack the extra languages (which is not a problem if you intend to play in English only).
Some games have text that is poorly filtered by Jabo's plugins (D3D6/D3D8), and certain settings are required to make it easier to read, like enabling/disabling the filters.