I wasn't trying to put words in anyone's mouth, I've SEEN people take this approach. I've also seen people warm up conventional and then make a max attempt sumo, or warm up bench narrow and then make a max attempt very wide. All of those practices strike me as high on the stupid-o-meter. And none of them have ever been uttered by Eric or IK (feel better about my disclaimer? )

I would say that switching to mixed grip isn't undertraining your grip on deads. If you can still hold onto the weight, then you are still gripping it. Just using some physics to your advantage is all. But no, I wouldn't say that will make your grip weak. I have also said that if you are worried about your grip, you need to train it by itself. Deadlifting is not a sufficient method of training your grip. That is not to say someone might not have an amazing talent for gripping and require no additional training.

I would say too that flexing at the elbow during a deadlift is a bad habit that makes you more likely to experience injury, much like rounding of the lower back during a squat. It might not happen every time, and we could probably find some high school kid who can squat 600lbs with good depth and a horribly rounded back who has never experienced an injury. However, I think that we can agree that weight aside it is a bad practice.

The other side of the injury game is that *gasp* steroids cause a lot of imbalances (muscle force and size accumulating faster than tendon/ligament capacity) and that congenital factors play heavily into how/when you will get hurt. So when we see the bodybuilder who gets hurt doing a certain kind of row with more weight than most people could handle... are we REALLY going to call that lift "dangerous?" Likewise, when we see a world class powerlifter break tibia squatting, are we going to blame that on squats? Do squats cause broken bones? No, that was a congenital issue (or perhaps ignored traumatic issue) that has come to a head. When I experienced my pec tear it wasn't that I was benching wrong. In fact, I had been benching for a decade at that point. Then, one day... snap, and that was it. No steroids, just a flaw in my body that had simply had enough. Heavy weights have a funny way of making it obvious where the weak point in the chain is. Biceps, backs, knees, etc.