There's some snow and ice, but just as much exposed rock (so still very hikeable without crampons or ice axe), and the weather looks good all weekend.I'm flexible and could go tomorrow (Saturday), Sunday, or Monday (I'm one of the lucky ones that actually gets Veterans' Day off work!)
I'm an experienced, responsible and sensible hiker who generally does a 2mph average pace on hikes like this (and doesn't mind taking breaks).
Diamond Peak is a bit less than 10 miles round trip with (I think) around 3K' of elevation gain. In my opinion, though a bit shorter and not as high, it's at least as difficult as the South Sister because the final ascent is a bit of a mess: somewhat challenging routefinding, and a jumble of pretty good-sized rocks and boulders to navigate. I think a comfortable time allowance would be 6 hours roundtrip (7 for an even more relaxed day).
Post up if you're interested!
Scott in Eugene