I've been eyeing one of these reels lately based on the rave reviews they have recieved. But, I can't seem to find that much of a difference between the SX and STX models. The only feature that I can find that the STX has that the SX doesn't is the Infini Spool 2 system which enhances casting. Just wondering if there is any other difference out there between the two that warrants the $50 price difference?