Whilst I'd obviously like to see as shorter save time as possible, I honestly believe that the most important thing is avoiding in game slowdown and stability. If it means that saving and loading take a bit longer then I'm fine with that.
Saving and loading are infrequent actions, and they're ones that you can basically be doing other stuff with. We're not in the days of computers only being able to run one program at a time - checking a few emails whilst it's saving isn't going to kill me, but 5 minute turn times will!