Just my opinion, but my 1907 back lock Holland is a joy to shoot with, easily as nice a balance and swing as my EJ Churchill XXV bar lock. I also note that H&H is still making best back locks, in guns as well as rifles.
Granger, afaik, island locks (and peninsula locks) are found in older hammer guns, where the lock plate is separate from (or only butting to minimally) the action body.