I got tired of trying to use the under seat lock. Too much of a pain, especially if I have a bag bungeed on the pillion. It's less of a problem with my new SeatSac. My solution is to use a padlock and lock the helmut to the the hole in the bracket where the hardbags mount. Obviously that won't work if you have bags mounted.
Hey Buck-- If your lid is worth more than 250$ I wouldn't use one at all. I know guys who lost Arai's, by thief just cutting strap and stealing & re-stiching it together.
Those thieves could be in for a nasty surprise if they ever need protection from the helmet in a crash. :bowl: I always take my helmet with me when I'm off the bike, removes the temptation for any low lifes.