Lee's are good bows. Like my old Wing.
But like Cacciatore already mentioned, the Stabilock(TM) is nothing else than the Slide lock system, which is around for a long time. The slide-lock is usually machined from solid aluminum adding a little mass weight, but was also slightly adjustable in windage. The Stabi-Lock is the same system just made from plastic without adjustment features.
The other bowyer is offering it for a long time for about $100 extra over his regular Imperial bow line. So it is still available. The Ultimate is no doubt a nice bow, but you can get the same features for a good bunch less $$ somewhere else.
I was smiling when I saw the BL ad for the Stabilock the first time.....