The grey yarn and I have been continuing our discussions and have come to a tentative agreement. The yarn was adamant about plain stockinette, but yielded in the end to just a bit of cuff detail. Of course, that won't show when I have a coat on, but I'll know it's there.
I'm not even sure where the yarn got off being so picky, because to speak quite frankly, it wasn't all that evenly spun. Remember the sport vs fingering conversation? The yarn wasn't being completely up front when it brought that to the table. I did catch it muttering something about "going for the handspun look".
All in all, though, the mitts will be warm and soft, and I guess that's the main thing. The weather's getting colder by the day. The second one's almost done. It's just on hold while I work on the Soaring Eagles mittens.