Oops, Leadfoot - I hadn't had my morning coffee when I posted. I have Platinum, not Mercury. :)
I have heard that the SLL group is one of the best set of plugs that Waves produces. That said, I have a lot of other plugs and I'm really digging the Abbey Roads stuff - RS56, HLS, Kramer Sig, as well as the CLA classic comps. The more I think about it, the more I wonder if I'm already set. It seems that I gravitate to a more vintage vibe with the Abbey Roads stuff (I'm an old Pink Floyd fan) and perhaps the SSL is a different sound altogether rather than something to compliment what I already have... I picked up the Slate VCC and FG-X too (haven't arrived yet), as well as the Maag EQ4 (Which I really dig).
Maybe before I got all of this the SLL would have been the bees knees, but now I'm wondering if it's a different set of crayons that I don't need for what I do...