Yes I've got the S550. I've been looking into the vertical link and lock outs for the rear irs.
crapatalk it sucks for free
Just googled a visual of your IRS, man what a clusterfuck! I didn't realize how big and overdone the LCA is on those cars.
Before pulling the trigger, disconnect your sway bar and rear shock. Use a jack to raise and lower the suspension in the corner and watch the movement of each bushing. It might be worth it to keep some OEM ones. YouTube videos don't always do it justice.
Eccentric lock outs are nice if you get indepent adjustable components, but that can be overkill and kind of a personal preference. I locked out the MS3 rear eccentric and running adjustable camber and toe arms. It takes longer to dial in alignment but it's much more precise if you want it.

