Ahh, my favorite subject.
I guess reading is too much for ya. Thats ok, im rusty on this anyway...
Pick the shock based on your weight, not how easy it is to put in or what all the masses of people are saying.
IIRC, the newer gix 600 shocks are good if your under 150lbs (these are also pretty short, so will need new dogbones) Gix 1ks are better if your 150-190 (almost same length), and 636/ZX10 are better if your 190+ (again, almost same). I would be looking for one that is at least 2001 or newer.
For any of those the install operation is pretty much the same. You have to cut the battery holder on the tank hinge and modify the battery box location. You will also have to move the battery slightly so that it will clear the new shock reservoir. Thats the short version, if you want more... look up something with pictures.
After you get shock in, be sure to set sag and adjust dampening to the middle settings.
If I messed that up somewhere, feel free to chime in... like I said, im a lil rusty on that info.