I just ordered a SlipGrip after seeing a post here a couple of days ago. They have one designed to fit the X in a Kraken case. They have a couple of different varieties depending on where and how you want to mount it. Haven't received mine yet though, so I can't comment on delivery or quality of it. It does looks pretty slick though.
My SlipGrip arrived today, it looks a little bit cheap, but has a pretty solid feel to it. Where they mounted the RAM mount on it looks like it was just glued on, but it feels very secure. It fits my X with Kraken case perfectly and it doesn't move at all, but it was still easy to get it in and out of the mount. So far very happy with it.
