Jason,as far as absorbing shock and vibration the 6"& 8" are very close in performance.
With a bow like the Legacy,I doubt if you could tell any difference between the two,except as for the balance.
I would suggest the 6" Stealth Hunter to you as the Legacy is already a very quiet bow.
I know several people that shoot the Legacy and use the 6" Stealth and say it balances the bow very nicly.I do get a lot of E-mails from people before & after they have puchased a Stealth stabilizer and get alot of feed back on what seems to work with different bows!
Hope this helps.
Jerry