Well the only thing I can say about these 2 is... I have an UltraXL, and it's one of the only stock Modules that I've played (Not that I've played a lot of stock Modules but..) that I like. It's sitting over there on a shelf, because I like many other (modded) modules much better. It's embedded in my mind that I'll never sell the XL. (Unless I sell it w/ the RM100 as a package). A friend of mine has an Ultra. All I can say about that is... I remember him saying he's "not impressed with it". I've played it (..because I've played all of his modules), but I was not impressed to the point that I don't even remember what it sounds like.
I haven't played mine in a while so its hard to give a detailed analysis of the tone, but... dunno if that helps.