The TF11's hopup is fixed and set for .2. They'll get you the best effective range of about 75-ish feet as you've observed. .25 will make the gun more accurate at short ranges, but the BBs will drop at about 50 feet or so. So for a secondary in CQB where all your engagements are short range, .25 are good. Otherwise, I'd suggest sticking with .2.