Jim -
To follow-up on South Sister: I've never done it in winter, but have done it 4 times in summer. Assuming the locals use the same trail/route year-round - I'd say the first couple of miles as it switchbacks up to treeline it might be a toss-up as which is the better "tool", but once you hit treeline and it levels out (more of less) for a couple of miles until you hit the last mile or two of steeps I'd say microspikes would be just the ticket. Of course, this assumes the snow is consolidated enough that you don't need snowshoes.
There are some mountains/routes I just wouldn't bother with microspikes. Whitney via the main trail and Shasta via AV Gulch is another. The first bit from Bunny Flats to Horse Camp is pretty mellow, as is the first 1/2 mile on Oberman's Causeway, but overall, it's crampon territory and microspikes would be unnecessary ounces.
Kevin
