Ok, I tried it out today, and here's my thoughts...
This actually solves a problem for me (albeit a small one). I only use Kong to load samples only, I never used the other generators. But one thing that always annoyed me is that each time I drag a new sample into the Kong pad, it reset some vital parameters (like % velocity sensitivity). Now, I could avoid this in Kong by opening up the little sample area on the bottom, and using the OPEN button to open a new sample instead. BUT, it was so much nicer to just drag samples onto the pads. ...And I just got used to it: Each time I loaded a new sample, I went and fixed-up all the parameters that got reset.
Now, with Umpf, it lets me drag new samples in, but doesn't reset all of the various params associated with the sample. EXACTLY what I wanted!
Um, I would have liked getting that small fix for less than $100, that's for sure.
Anyway, overall, Umpf does exactly what I want: A bank of samples to trigger, and wonderful of-course in-conjunction with the Drum Player.
One more thought: It's SOOO nice to be able to create a Combinator with Drum Player and Umpf saved into it. And I have Microtoniq, which I really only use for kick drum - so very easy to save that into the Combinator too, and use gate on one of the slots to trigger it. I use a Mixer to sum the output from Umph and Microtoniq. And since I have a mixer, what a GREAT way to setup Send-effects of Reverb and Delay. So all-in-all, it's just SOOO wonderful to get this all setup in a Combinator and save it with my favorite VST Reverb, etc. ****We seriously are spoiled in Reason.****