Recount does work in nUI -- it will appear in nUI's info panel in the lower right... there's a red button in the bottom left corner of the info panel... click it to rotate through the active panels. There will be one there for Recount. The default nUI+ distribution also supports Omen3 and Skada as well as the battlefield minimap and combat log. There are optional info panels for other mods such as Grid, Healbot, etc.
I am unaware of any compatibility problems with RatingBuster either and best as I can recall, there are nUI users that use it.
You can find a list of known issues at
http://www.wowinterface.com/forums/s...ad.php?t=21532 -- Otherwise, I am not aware of any problems with using other mods with nUI.