Sorry, I must have missed this post the first time around.
Yes, I've run two full sets of ME880's on my '07 GT, for ~20K miles.
First off, they don't make ME880s in the correct size for the rear of the GT (180/55-17). The front tire is no problem (120/70-17). You can run a 170/60-17 ME880 on the rear without any problems, except for the normal 880 issues of front tire cupping and howling, severely reduced handling in the corners, excessive squiggliness over painted lines and tar snakes, and complete lack of traction in the wet. Other than that, they're fine.
I did get 12,700 miles in about two weeks from the first rear (almost exclusively highway miles), with the front still looking good. The second rear only lasted 7,800 miles (lots more back roads), while the front still looked new. But I hated the tires the entire time I had them on the bike.
In fact, I still have some half-worn 880's hanging in the garage for my GT and my old LT, and I just can't be bothered to put them back on. Nope, no thanks.
'13 Dark Graphite Metallic K16GTLD, 24K miles and counting...
'09 Magnesium Beige Metallic K13GT, 60K miles miles and counting...
'02 Mauve Metallic K12LTC, 106K miles and sold
BMWLT#145, IBA# 366, MOA# 111996, SCMA# 24032
All lower 48 states plus Alaska on the K13GT in two weeks . . .
Some people see the gas tank as half empty. Some see it as half full. All I care is that I know where the next tankful is coming from...