I also have the UUC SSK. It is definitely an improvement. Takes out the slop in the shift linkage. It will require a little more effort at first, but soon everything loosens up and the action is nice and slick. IIRC, you need to also get the DSSR which adds to the cost.
For something that you will be using a hundred times a day (o.k., I exaggerated), it's worth it to buy the best you can afford.
Here is a nice link to UUC's site which explains the differences between stock and UUC's unit.
I am using the weighted ZHP knob. (My original knob broke and when I ordered the new one, it was heavier although they looked identical).
Johnny
2004 Imola Red over Black Leather. 6-MT, Navigation, Cold Weather Pkg (the wife loves them seat warmers!), 3.46 Diff, UUC Short-Shift Kit, Tranny Mounts, CDV Delete and iPod mount.