Could not agree more.There's no way.
If you replaced Federer's backhand with anyone else's on the tour, he would lose all his variety on that side. The offensive and defensive slice when pulled out wide, the flicks, bunts, dips and lobs, his ridiculous drop shots to the deuce side, the general control and soft hands he has on that side, his consistency. The only area that maybe would'nt be hurt if you gave him Gasquet's backhand would be the topspin drive, but even here we cannot be sure. Federer gets a lot of variety on his topspin drive, the short cross court pass, the different trajectorys and the general pace and whip he achieves. Gasquet's topsin backhand works more like clockwork, it is a reliable solid shot with good pace and spin, but it is the same each time and not particularly scary if you are not at net. Kind of reminds me of Pioline's backhand, easy and fluent enough, but not especially potent.
If you replaced Nadal's backhand with anyone else's on the tour, he would lose the pace he is able to generate when he counter-punches off a driven shot, his ridiculous gets when stretched out wide, the angles and spin he is able to create, the variety of ball he is able to deal with offensively, the general control and effectiveness he displays from that side, his consistency.
To replace either of their backhands with anyone else's on the tour, I believe would hurt them. Maybe you could take one or two aspects from someone else's backhand to improve their game's, but not the whole package.
Sometimes I saw Gasquet a little bit overused his BH. So it could be a reason why his BH look the best. I think he prefers to use BH instead of FH. Until his FH helps him win one GS, I still rank it below Fed & Nadal BH because of variaty and power. Anyway Gasquet backhand certainly in top 5.