I can't elaborate a lot
The only things I can say is :
- when you say than "Stan has more flatness and power", actually Gasquet can hit it flat and powerful as well ;
- videos might be helpful but I'm at work and have no access to youtube.
Gasquet has a less offensive mind and has a very far court-positioning but it's only partly because of his backhand imo (it's also because of his mind and footwork, and because of his forehand), because yes he's more comfortable when the ball is low, that's the ideal conditions for his backhand, but I saw him hit great backhands on high balls as well. And Stan also is more comfortable when the ball is not too high.
Any tennis player can hit the ball "hard" and "flat", but it's how you adopt this style and bring it to the court. Gasquet is capable of ripping excessively powerful BH's, but elects to be more precise and angle-driven (which is beneficiary in the long run), whereas Warwrinka pushes and attacks with much more frequency and manages to give it incredible pop. Both are impeccable for different reasons. It entirely depends of the surface, as well.