suspended chain good mornings have become one of my favorite exercises.
we use 3/8" chain to suspend the bar. be careful. the chains wont break even if you slam 800+ lbs into them but the carabeeners (spelling???) you use to hold them together might. we put safety bars in just below where the chains suspend the bar and sometimes we double up the carabeeners.
when i use a close stance, i think they come close to simulating my deadlift because they start from a static position.
when i use an ultra-wide stance, they really seem to help that lockout portion of my squat.
we use a variety of heights. of course, the heigher we raise the chain, the more weight we can use.
i have a TON of videos of us doing good mornings at various stances. www.growordie.com/training/videos
just look for all of the titles with good morning in them.