I have and use the Xede - but I really don't see any reason to jump any ships. If I had already had a UTEC I probably would have stuck with it. I would like to see more active users of Xede to create an alternative ship for those that haven't boarded.
Timing is just one of UTEC's big pluses. It takes over timing and provides knock correction even along the ragged edge very well. Though the comments from some users would indicate to me they aren't well prepared for what that means with comments like - "I am getting a lot of knock, is knock bad?" To some extent having a tool that rides the conservative safety features of the ECU could be a plus for some users. Tuned properly there should be no sacrifice and some self-tuners would be protected from their own agressiveness.
I went with Xede because I like the TPS transitions I have been able to map, its boost control is much more intuitive to me resulting in smooth curves with little effort at POT or WOT, the available loads and load points provide me with options I like, the interface is great and I can see visually in real time where I am on any map.
Do I wish I had the option to take over timing - yes. But I am pleased with my current experiences with a timing overlay map (hmm how many timing maps are involved in determine my timing now is it 3 or 4
Do I wish there was more documentation - absolutely and anyone who has followed other threads knows how emphatically and continuously I am begging for some. (How many years has it been waiting on the WRX tuning guide? Oh wait they pulled those references right...