I've done it, using 4 rear 161s and Continental DW 255/40R17's. I'm totally stock and it fit fine. I've got two sets of staggered 161s, I'm using the 8" fronts for "winters", and the 8.5" rears for summer tires.
It definitly increased grip a ton. Steering feel took a hit, but I think it was more due to the switch from potenza runflats. I definitly felt more body roll, because it would pull more G's and overwhelm my stock suspension instead of breaking away.
I did it for the same reasons you did, tire rotatablilty and increased fun. I like the increased tire life (25k on Conti DWs and still not to the wear bars) but I'm not sure that it made the car more fun. Maybe if I was tracking the car it would make sense (with higher spring rates), but my BMW is a DD. If you want to drive to NC to get them, I'll sell the 4 rears to you.