Couple of things, if you get comand you can add Dab for around £350, no coding needed.
You should be able to choose bluetooth audio streaming from the service menu on comand if it is not already there, needs to be a certain firmware date to do this, but if you go for a later car with 7G+ gearbox you should be covered.
Definitely go for a later car from mid 2011 onwards so you get the 7G gearbox, it is worth it imho, plus the tech is much better. Harder to tell on the 6cyl, colour instrument cluster, straight DRL, lower emmisions are all tell tale signs, but some anomalies out there too, and dealers list them incorrectly too.
Also, I know they are rare, but consider the E350cgi as well, I went from cdi to cgi and the difference in refinement is massive, the whole package just feels right, and the MPG is around 10-15% different, for me doing 20k miles a year it is costing me about £7 a week more to be in the petrol.
33.2mpg from the cdi (36 on the obc) and 29.7mpg from the cgi.
Also, although the alcantara is tough, the plastic on the bolsters is a weak point, lots of cases of that mbtex or whatever they call it these days ripping. I would try and find one with the full leather, on the sport it is really nice leather and comes with contrast stitching.
Try and make sure you get the Intelligent Light System, that is a great option.
Standard stereo is very good, HK actually sounded a bit bloated at the bottom and shrill at the top, I wouldn't bother.