Also, in a game long enough to go past 10 mins (after calling Ace), with a normal tiger doctrine, you quite probably called 2, if not 3 Tigers, all while reinforcing your army.
10 mins @ 200-220 MP/min = 2,000-2,200 MP, so manpower wise you are pretty much correct: you'd have the manpower for ~3 tigers. But there is no way you'd be able to generate the 600 fuel necessary.
Also, having 2 Vet 0 tigers is less potent imo then having the Tiger Ace. If properly supported, that thing is a BEAST. Speaking as a soviet player, I'd rather deal with 2 Tigers at once then one Tiger Ace.
Also, you can easily save on manpower prior to calling in the Ace in order to be able to reinforce your army during the 10 mins (I usually float 800-1000 Mp before calling in the Ace). You don't really need that much manpower anyway, since you're gonna be on the offense and dealing way more damage then you will incur.