Well, I would think that the more surface area you have to dissipate a set amount of wattage, the better. More FETs translates into more surface area to handle the same wattage (heat we need to dissipate). But with that said...

The only thing I would be conecerned with is if there would be some sort of inefficiency with driving that many FETs? I mean, each FET is only efficient to a certain point, and what about switching losses? More FETs means more wattage lost due to switching loss no?

Interesting problem posed lutach. I'm going to keep an eye on this thread to see what the general concesus is from Patrick and Artur (and anyone else who's an EE- which I am not).