I looked hard at the Mercedes SLK55 and the SL500. I couldn't afford the SL500 (ouch). The regular SLKs (350, 280, etc) didn't have enough horsepower to really compare. The SLK55 was almost impossible to find used with fairly low miles. Although the SLK55 is a great car, it just seemed too small for me. My daughter said "you look like an elephant riding a peanut" (referring to the short wheel base and short overall car length). Mercedes made a big deal out of their hard top retracting in 19 seconds vs. 30 seconds for the Caddy. My only trouble on the Caddy has been the computer thinking the top isn't fully locked when you hit a hard bump. That has been fixed now via some reprogramming.
The retractable hard top is killer. Only Mercedes and Lexus have something similar. The RF key fob is awesome. I never have to touch the key at all to handle locking, starting, etc, etc.
Allow the retractable top to be run via the key fob from outside the car.