I think the title of the thread is a bit misleading. People choose/use Serpa holsters because they want active retention. The gun won't come out of the holster unless something is deactivated/pressed, etc. X-Concealment doesn't use active retention. Saying that the X-Concealment stuff is a good alternative to a Serpa is like saying the Glock is a good alternative to a Beretta for someone who's looking for a gun with an external safety. No makey no sense. Apples to Oranges.
X-Concealment stuff looks like a good option for Kydex holsters in general though. However, they use 0.093" Kydex for the outside sheet and 0.06" Kydex for the inside sheet on their C series holsters. They don't say what they use for their M series holsters. Unfortunately, the use of 0.06" Kydex makes the holster line a no-go for me.
I've used Raven holsters since they started out years ago (when their wait was less than 28 days). All of their earlier holsters (pre-2009 I think) were made with ~0.06" Kydex and they all (the ones that I had) cracked over time (The G26 holster cracked at 6 months... the G19 holster cracked at 9 months) under normal daily CCW.
The cracks developed at the high stress/flex points... pancake wings, edges of the holster that were in front of the ejection port, etc. I informed Raven and they told me this was a known issue (not with Raven holsters, per se, but in general, that 0.06" was just too thin and wasn't durable enough) and that they already changed over to using only ~0.08" or thicker Kydex. Because of their unconditional lifetime warranty, they sent me replacement holsters free of charge within 2 weeks.
My ~0.08" thick Raven holsters are holding up great after years of daily CCW. And I think their unconditional lifetime warranty is something that sets them apart from the rest of the shops trying to compete. I don't see anything about a warranty on the X-Concealment website.
I spend $75-80 on a Raven holster and wait a bit... and get free replacement holsters for the rest of my gun-carrying life to replace the inevitable worn/broken holster. With most other shops you'll have to keep forking out the $45-65 for a new holster every time your holster breaks.
Anyway... food for thought.