I've finished my testing, so a mini ball review. A recap of balls I'd already tried:
Dunlop Fort: very heavy, lack of bounce, like hitting bricks when it was cold.
Slazenger Wimbledon: decent bounce, fuzzy up very quickly, didn't retain pressure too well.
Wilson Championship: lighter than premium balls, pretty rubbish after one outing.
Tecnifibre X1: retain pressure well, don't fuzz too badly, expensive.
And the three I play-tested:
Wilson US Open: didn't have that uncontrollable 'just open' feeling when they'd just been opened. The felt stayed nice and tight for the first session, then started fuzzing up. Have retained pressure well.
Wilson Australian Open: as with the US Open, not too bouncy when fresh. Fuzzed up very quickly. Good pressure retention.
Head ATP: bounced a lot initially, didn't fuzz too badly. Had lost a lot of pressure before their second outing, far more so than either Wilson ball.
All three had a decent price point when buying in bulk, being over a pound per tube cheaper than the Tecnifibre. I've got a few tubes of Tecnifibre left, so will open one of them as a final test: right now it's either stick with them or give the US Open a run. I'm also tempted to switch to 3-ball tubes and open them more frequently: 3 is plenty when playing sets, and there are only a couple of people who will drill with me.
All of this was on carpet.
My String Journey: http://tt.tennis-warehouse.com/showthread.php?t=362403