I took up the Digital Performer 8 cross-grade offer a few months ago after trying the demo, and for a while was seriously thinking of switching. It has a very different workflow, but one that makes sense once you spend time with it - it also seems to run more smoothly on a Mac than C7, and themes are great. But expression maps, the score editor, chord track, included instruments, etc. etc. (not to forget this forum) made me decide to stay with Cubase as my primary DAW. I'll keep DP as a second DAW though, not least for the quality of the included plugins.
I did buy Logic X because it's fairly cheap and I've got a lot of old Logic projects. But I still don't like the way that it handles multi-timbral instruments, and am becoming less happy about being locked into Apple.
MacBook Pro 13" Intel Core i5 2.5Ghz 4GB RAM, Mac OS X 10.9, Apogee Duet Firewire, Yamaha S90, Cubase 7.5, Komplete 9, HALion 5.0.1