I have the MKi9200 installed. I use it almost exclusively with bluetooth for calling and for listening to podcasts.
I have the Bose setup in my car and had to get one of those wiring/amp kits. Install was straightforward although it was a bit of a pain to stash the boxes in the dash. I get a bit of alternator whine but not enough to make me really want to rip everything out again.
I thought I would like the screen a lot better than I did... other than seeing callerID or settings, it's not much use... If you listen to USB music or SD, I'm sure it's handier.
Overall, it's a nice kit and they update it regularly with updates to primarily support the iPhone. Would I get another one? Probably not a MKi9200 again as some of the extras aren't worth it in my case.