I pondered the same thing and ended up calling JonB for answers. He said there's no way you could tell the difference of a 1" drop in one of the seats and not the other. He also strongly suggested the 1" drop to retain the ability to move seat ahead/back.
He was exactly right! I installed the 1" kit on drivers side only and you would never know it, and as most Viper owners I too am very anal. Not only does this save me $280 by not doing the passenger seat, but the 1" drop was plenty. MUCH more comfortable.
I also took Jon's advice and removed my drivers side visor. I never use it and it really improves my field of view out of the drivers seat. If my wife never drove the car, I probably would have gone with the 2" drop since 1: It's cheaper, and 2: it would have given me the most leg room possible.