The data you named (several hours vs 15 mins) in fact was the data I was interested in 
(Assuming fairly unchanged data.)
Thanks for sharing!
…which doesn’t differ from your idea/implementation, does it? (except using some mount mechanism instead of symlinking)
Or did I miss something about your implementation?
Still confusing me is the following:
Sounds like he didn’t get benefit from the similarity amoung all his backups…