I have a 696, in fact I kind of designed my panel around it (experiemental - Rans S-7S). I think Garmin is just the shiznit in some respects, and in others, I think they really have their head buried in a hole - probably their own.
I would love to try out the Cheetah. I love the idea of being able to add an actual AHRS to the system for attitude info should my judgement fail me (e.g. the judgement to be out flying when I would need it). I think it also looks like an amazing little unit, and it's priced great. Lots of good reviews here. I would love to get some time with those units.
I have few benchmarks except my old Magellan POS. I had a 496, have flown w/ the 530/530 and some time in a G1000
696 Overall - I love the unit. That's got to partly because I paid all that money for it, but it does the job very well. Its got a big screen, has more of the navigation speed/ease of the G1000 (due to the multifunction knob/wheel/button/joystick). The weather is great, immediate to access without much button pushing - as is waypoint, XM radio and other stuff. If I had to guess, I would say that overall it's probably low pilot workload to access common critical info than the tablet PC-based units like the Cheeta, but I have no personal experience with that. I also like that you can have the "panel" page and other stuff on without ever leaving the moving map. I think the Cheetah does that too.
The scrolling on screen to pan the map is annoying as John says.
The one thing I would pause with, is that every PC I have has an issue at some point. Some probably because I am loading all sorts of different software on and stuff. That wouldn't be the case with the Cheetah, so maybe its not an issue. But I just somehow get a little nervous using Windows, PC, and primary navigation device all int he same sentance.
But the GPS is my primary instrument in a way. I have no VOR or other radio nav aid. My iphone works good as a back up GPS in a pinch. But I think its hard to knock a garmin for good old reliability. Its gonna work.
The updating is part of the head in a hole part. It's rediculous considering how good they do everything else.
I also wanted an easily removable in-panel mounting system, meanin Air Gizmo - I had I think the 3rd one out of their mold.
If I had to do over again, I think I would play with each unit for one hour. Set up a typical cross country simulate flight and "fly it" - e.g. go through all the things you find yourself doing durin a flight, or that you think you will.
Here are some pics of mine mounted.

