I would personally go for the SL500 Spinedoc.
I know, I know, "an SL 600" would be wonderful! But I agree with texan's posts, and his comes from first hand research on the topic. Try a 96+ SL500... the 96's come with the slightly updated exterior as well,
And, an SL500 still hawls serious @ss! And it's your dream-car/roadster... make it the best experience possible! 96 or newer SL500.......!
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)