Excellent Review Gordon, you left no stone unturned and I really appreciate that. Recently my G12 fell victim to theft so in replacing it I'm heavily considering the G1X over the G12. Lots of food for thought from your review. Having been heavily invested in Canon products for the past few years, especially in familiarity with the Gx line and having Canon Speedlites, I feel more weighted to the Canon, but that GX1 is tempting.
You're absolutely right about the horrible continuous speed. It seems like it's plagued the Gx line forever and I was really hoping they would have improved it with the G1X.
The loss of macro options is a real bummer too. Shooting macro with my 5D Mk II is superb IQ, but takes a lot of setup, tripod, etc. so I reach for my Gx a lot of the time for simplicity and spontaneity. Guess that's out.
The sample images you got as jpegs right out of the camera are really impressive in IQ (viewed your originals on Flickr)! Looks like auto WB did well and the colors look natural and nicely saturated.
I don't know, I'm really torn about it for all the reasons you put forth in your review.