I've been driving on a set for over 3 years, summer and winter, and still have plenty of tread left. If they do wear "quickly" at higher temps, for me at least they don't wear quickly enough for it to matter.
No -- they're still superior to all-weather tires in snow and ice. If you get a lot of that, they may be worthwhile. E.g., https://www.youtube.com/watch?v=8K8ThRGNaoM
Spreadsheet: https://docs.google.com/spreadsheets/d/1Smk69SCu5WrI3yRd_FO6...