After I get this conversion working (having some shifting issues at the moment) I'll look at 12-28 for a RD. We could do 95+% of our climbing using a 28, but I'd need the 32t as backup for a sustained steep climb. It only takes a few minutes to change cassettes, not on the fly of course! I don't have really a choice in chainring being on a daVinci, but the closer spacing shoud decrease the number of times I have to double-shift on gentle rollers or into a headwind.