i would say the lowest riding folder around 3 inches would be the Gerber SLG.
i have one and i love it, the lockup is great and so are the materials.
It rides almost as low as the SERE, but tip down.
they only things i don't like about it is the finish on the G10 scales seem a little slippery and need some getting use too and the pocket clip, althought it's a great design, is a little too weak for my tastes. it doesn't really clip tightly to my pocket.
i haven't had any trouble, but i'm always scared i'm going to lose it. being really low helps it from coming out, but i keep mine in my pocket now, not clipped to it.
------------------
~Fumbler
the crazied knife weilding Sarah McLachlan fan =)