purchasing consultancy SLK 280

hi, come from the e60 forum (bmw 5er) and look for a nice cabrio that is suitable for everyone in my mind Z4 2.5si (r6, 218ps) and SLK 280 (v6, 231ps). we stay with the SLK. how is the motor? enough the power? higher PS can not be afforded by insurance technical reasons I tend to the hand switch, but the question is, is an automatic transmission of MB (don’t know me at all) more useful than a hand switch? should I consider something regarding EZ? thought about it this way 2007 because these were now significantly reduced price. I drove the z4 test today, as I am used to from BMW, was the car of all first visions, the feeling and especially the engine sound impressed me, not to mention the processing, which I hope from MB can also hope to this MB? http://www.autoscout24.de/Details.aspx?id=leubkujw1mtc to identify any defects or errors? missing what about the equipment? is the vehicle with KM a no go? should I rather buy directly at the friendly MB dealer? ask about questions edit: the vehicle has automatic, could I possibly upgrade steering wheel shift paddles? would then be important to me, not to mention the new rims so, so I would have that for the first time. thank you for first pheeR