No it's going to sound the same. But will have the potential to get louder due to the extra power. Out of the two you listed I would choose to run the p3001. It is a very solid amp.so even at low volumes the sub will sound better with a more powerfull amp that is not being used at its full potential?
I don't know what you mean by "economical". But it will actually produce a bit less power than the Fosgate. They are close enough to just pick the unit you think looks better and is cheaper. If you don't like a lot of bass output, you can always lower the volume/gain...so wouldnt the JL be more economical on the power?
and sq between the 2? buid quality? reliability? efficency?
SQ - boils down to everything you listed. Mainly the build quality of the amp. So neither one can claim to have better SQ.and sq between the 2? buid quality? reliability? efficency?