I had the analog stage mods done, but am holding off on the clock upgrade, as I need to be able to slave it to my UA5 to run a 4-mic mix, which is why I bought it in the first place, and the clock upgrade would not allow that. But I'm thinking of getting rid of the UA5 and getting a DAV BG-1 or a Sax. If I do that, I'd get the clock upgrade done, also, since it would be an analog input instead of a digital input, and I'd actually be using the internal clock.
I didn't run the Ultralite much before the upgrade, and I'm mostly running it now in combination with the UA5, so I'm probably not the best person to speak about the improvement. But, in the little testing I did with this unit alone before and after the upgrade, I think it was worthwhile to have it done. I should do more listening to try to describe specifics, but my first impression was smoother highs, better soundstage, and maybe slightly tighter bass but I wasn't listening to the best source material to judge the lower frequencies. I know the prices just went up on the mods, unfortunately--I got mine done just under the wire.