The big thing if you go with target minutes is to under-allocate them. The biggest danger with minutes (and this would be even more so with a FB/FCP team...) is that, say you have your PG set for 24-28 minutes. If he gets in foul trouble the first half, gets 3 fouls and winds up playing only 8 minutes as a result, he might wind up playing the second half non-stop in an attempt to "get his minutes." This is also the case for a player who gets injured and has to leave the game, but then comes back in the second half. Again, they'll play to try and reach their minutes, even if it means playing at very tired for minutes on end.
Needless to say, this sucks.
I've avoided these issues by under-allocating...there's 200 minutes in a game, I assign 160-170 of them typically. If its a blowout, the engine gives the "extra" minutes to my reserves. If its a narrow game, the "extra" minutes go the starters. With a Motion/zone team, this has worked fine and has given me great control over my minutes promises. For a FB/FCP team though, I think I'd go fatigue because keeping fresh bodies on the floor to avoid fouls is a premium.