Can't go wrong with either really, you are correct in that the Crew will handle water conditions that will flip the UL-1, the UL is also set up to turn right only!
One of the guys I run with has a Revolt and it runs very well also, there are SV-27's UL-1, Motley Crews, Revolts and Stilettos in our group plus a number of full on race boats.
Keep in mind all of the RTR boats are built to a price point so don't expect any of them to be ''perfect''. When run as intended on the recommended power the will run reliably for a long time at a pretty reasonable speed.
I have a Crew and am happy with what it does, it's reliable and stable, but I know if I attempt to power it as some of my others the hull will not survive very many crashes, all of the RTR boats are a pretty thin fiberglass layup and tend to develop stress cracks in the same locations.
To put it in perspective a full on 4s race boat is about 1000$, what we have are about 400$!
They are a great way to get started in the hobby and learn the ropes of electric boat setup, then most people start rolling their own from bare hulls.