I have small feet and high arches and even with the strap high on my foot, at an angle to the pad, the smallest straps, and the toe curl technique I lost my board lots.
I have had the Liquid Force heel straps for all of this season now and it makes a lot of difference, tho in my experience the board still comes off fairly easily (including mid jump!) and I havent hurt myself yet. It does take a bit of time to get the board on, and I couldnt get it off quickly when trying to get onto the beach to chase after thieving bastards taking my gear bag

, but better than a leash I reckon.
However, the other day I set a girlfriends board with heel straps made from sections of push bike inner tubes (as suggested elsewhere on this forum) and this seems just as good and a lot cheaper (Free!).