I fly roughly 30k PQM a year, and it's totally worth it for me to get do extra to get to Silver if I happen to be a little short. I upgrade to E+ on every flight, with 2 upgrades to First last year. The 24 upgrade window comes earlier for me than other silvers - since my itineraries start in Laramie at 6am, usually early enough to get my choice of E+ on all remaining segments.