I wasn't going to comment so as not to stir up feelings, but, well, I know that Pammy will disagree (sorry) but the old SLK isn't up to much in the sports department.
The roof is fantastic, the interior is fine and the chassis is fine, too. In fact everything is just fine. But, if you are buying a sports car - this isn't it.
Consider it as a very pleasant Grand Tourer (say for a nice gentle trip to France) and it is on the nose. But if you want to do a little "canyon carving" (as our US friends put it) then I would strongly recommend spending your money elsewhere.
I haven't tried the AMG - I suspect that may be a different kettle of fish!
It depends on your budget. Have you thought about a 3.0 Z4? Early ones go for around £22K and will leave a non-AMG SLK for dead in the twisty bits. Or perhaps a Vauxhall VX220 - very desirable to my eyes.
Good luck.
Philip
Post posting edit: Never had any problems with mine. Nicely built, etc.