I think of UM as what you buy when too broke to buy better. And then only to tide you over until you have enough money for something good. If you need affordable kydex it's hard to go wrong with Comp-Tac. Or kydex/leather hybrid IWBs from Comp-Tac/Minotaur or Crossbreed.
I just bought one for competition. I received advise on this site to go with the cheap stuff till I'm sure I like competition and then get something else. I think it is pretty good for a Kydex holster. I am not a fan of Kydex, but like you said, it seems to be the trend for competition holsters. It was $17. I think the other stuff is VERY overpriced because of the name band. I think the UM rides a little too low to wear concealed and its going to be a bear on my finishes. I will order a Wilson Tactical Assault at a later date.
I own one UM that is nylon, not kydex. I wore it one time. At the range I bent over to pick something up, and the gun tumbled out of the holster onto the ground. I figure it's a non-repeatable event, a fluke. Not having learned my lesson, moments letter I bent to pick something up. Same result.
Yes, it was a holster made for the gun. From that point on, whenever I needed to pick up a readily available production holster, I went to Galco.