I haven't done any 'hands' tests.
Eventually I'll get the entire right side of my line (C-RG-ROT) to invest 6 in it and hope the effects compound. I think the text SOUNDS good but nobody has any evidence for it.
The thing about hands is it's one of those "rich get richer" things, like pancake, showboat blocker, etc. If you're good, get pancakes, etc., you might as well do pancake/hands/showboat blocker and run the ball a lot and just demolish the d-line. But if you are outmatched, this wont help even the playing field I don't think.
Now, I realize that is precisely the OPPOSITE of what the SA says, but I just don't think it will help make up ground as much as other options. Plus, I prefer to build to be better than my opponent, even if it means spending a few losing seasons to get there.