I think your chances are pretty good. Out of four, I got three that seem to be perfect, and one that was a bit ‘off’ to begin with - but a piece of wire in the tailcap, and constant use seems to have worked out the kinks.
There are some things that might be worth paying attention to before you ever put a battery in .
Check the five little prongs on the back of the driver to see if they stick up very high. If they do, trim them before you install a battery. If a flat top 14500 were installed, all they’d have to do is stick up higher than the “+” bump on the driver to possibly cause a short.
Check to see if there’s any gap between the tailcap and the tube. Some of mine have measurable gaps, while the problematic one had no gap at all, and I think the ano on the cap was meeting the ano on the tube shoulder before the circuit was made. A circle of copper wire inside the tailcap fixes that., and even adds enough length to accommodate slightly longer batteries.
I’ve only had experience with the one troublesome light (which is no longer troublesome), but I have learned a bit and tried to put to use some of the clues posted about the UT01. The foregoing only might help. I can’t comment much on possible 14500 issues; I don’t use them.
You mentioned the switch (as have several others). Mine had a ‘crunchy’ feel to it when it arrived, almost like 3 or 4 steps in the brief length of its travel. I think it was internal debris of some sort; it actually smoothened itself out to where now it’s indistinguishable from the rest of them. Others have reported worse problems, so YMMV.
I’ve been using this ‘problem’ light hard. It has rarely left my hand since it arrived a few weeks ago, and it’s gone through about three NimH cells and a couple of Lithium primaries as a night light, a table light, and to light up rooms instead of flicking on a wall switch. I’ve been trying to make it fail, and instead it just got better.
I’ve been lucky; I hope you will be too. I think your chances are pretty good.