Some very good points. I agree that most injuries occurs due to some sort of accumulation of things and not usually right off the hop, with their cause being virtually undetected until injury. That especially hits home with deadlifts since, like you said, the weight seems to skyrocket in no time.
I like doing the ghetto's because I don't have to worry about grabbing a pair of handles (the machine at my gym has two small handles just ahead of the knee pad on either side), if I need some assisstance or a 'safety net' I can go into some form of a pushup. But I suppose if you're really prepared for the machine and you're ready to grab the handles, it would be just as safe.
I guess the long and short of it is, I would suggest GHR's if I knew the person was capable of safely executing the exercise (assisted or otherwise). The same can be said for almost all exercises. I'm also going to say that I agree with GHRs being an excellent exercise, somewhere along the lines they should definitely be introduced into the routine. The suggestion I've made to some people that I 'coach' (I use that term very very loosely) is to do some wide stance squatting when GHRs are not really much of an option (ie more assisstance than actual exercise), and have some pullthroughs mixed in as well. Just something to get the glutes and hams involved by something other than hamstring curls. I'm not 100% sure if I'm right in doing that but it seems to have worked for myself and a few others I've helped.
Oh yeah, he hyperextended his knees basically because he, imo, panicked. Coming down his glutes and hams couldn't slow him down and he tried to grab the handles but didn't get a good grip or missed them (I'm not sure which) and basically ended up at the bottom of a reverse hyper supported by his knees.
