I do enjoy the flexibility of "TotalMix" with the UFX; was the upgrade a "life changer" over the i/o of the FW?
I really don't think so.
Ultimately can I run with slightly lower latency; pretty much.
Maybe the improved AD cleans up the mix, IF you are using lots of live tracks.
The way I work, a few guitar tracks, a few vocal tracks; I'm not sure its huge.
Tom