The only thing about being given the Heat match is that the crowd knows the match is like a 'warm up' for them (and the arena is often not completely full at that point) so are usually quieter than during the PPV itself, which detracts from the match slightly. Also as the match is on at the end of Heat, you know how long it's going to last, whereas on the PPV you don't. But yeah, given the choice between a 15 minute Heat match for the cruiserweights or a 5 minute PPV match, I'll take Heat.
Incidentally, I am really looking forward to the Rumble, as yet there isn't a single pointless, shitty matchup...so what's going to be added on Monday to bring the show down a notch? Cade vs. Rosey? The in-ring return of Rodney Mack? An Austin sing-along segment?
Evolution vs The Dudleyz is pointless because Evolution has beat them 2 times without much trouble.