The FlipBelt looks very promising, and possibly even more comfortable than a SPIbelt. (I find the clip on the SPIbelt uncomfortable sometimes.) The only thing that I don't like at first glance is that the smallest size it comes is 25" unstretched, which is too big for younger kids or small adults, despite it saying it would fit a 22" waist. If they would make a smaller one, I'd definitely buy one. (Maybe I can make my own - it's such a simple design.)
The Fuelbelt I've seen in person and know a few people who own them and really like them. They look pretty but don't hide well under clothing due to multiple seams, gel loops, and zipper placement. It's great for over tank tops or running gear though. I like how the clip is on the size instead of in the middle - more comfortable than SPIbelt in that way. I haven't tried stuffing an EpiPen in the pouch though, and I'm not sure if it would fit. (I haven't been to run club since last summer, and I seem to think the pouch was smaller than the SPIbelt.)