I don't agree, I think the SLC will always be hindered by the fact it's never looked like a clean sheet design. It has awkward proportions with the two ends stuck on. The Boxster/Cayman's success is that its design has its own identity, it's been designed with less interference from other cars in the range. Even the Z4, with its kidney grills, still looks a lot better.
Merc have done a good job in getting the new C-Class Coupé to look like a clean design, it looks like it was designed to be a coupe all along rather than a saloon that's had 2 doors cut out like the model it replaces did. It's a shame they didn't take this philosophy to the SLC.
The SLK/SLC always seems like a bit of a bodge job, a bit of a quick 'put new headlights on, offer an engine we offer in a different model, add an extra LED into the taillight and call it 'BRAND NEW MODEL'. It's why I don't think i'd bother with it.