Just received my SGP Carbon Skin Guard & Ultra Crystal SP today as well and I'm loving it. Going to wait for my black
Bumper to arrive before install though. Currently using the Zagg IS full body and liking it as well. Took a little getting use to though but was a super easy install. In the end I think I'll remove the front Zagg SP and run with the Ultra Crystal and just layer the Carbon Skin Guard over the IS on the back.
How did your Ultra Crystal SP seal up around the mic and home button cut outs? I have been reading posts that there is a problem in these areas with the Ultra Crystal SP.