My one has the headlight washers, but no cruise control, manual steering column adjustment, no heated seats and no rear blind.
I love it - it's very simple - I don't want the rear blind because I want to see out the back (and how often do you carry rear passengers in an E31?), the heated seats are an irrelevance unless you park the car outside in winter (shame on you if so!), I don't ever change the steering position because I don't generally let others drive it (just my wife, sometimes) - the only thing I've ever missed is the cruise control, but even that's not a really big deal (would be if I lived in the US).
Do see if the car has the more tinted rear window, with graduated tint towards the top - that can help reduce rear glare. Far more important to be rolling on the right rims (Alpina, ACS or Hartge only, thanks!) and with uprated brakes...
If you MUST drive a Merc SL (really, just because of a lack of rear blinds???), make sure it's a 48-valve SL600 - the full 400bhp beastie, not its wimpy successor. Better yet, find yourself an SL73 AMG. There's at least one in London.
Or if you fancy a really nice and well-sorted late-model 840Ci Sport, make me an offer! I'm still unsure of whether to keep mine or not...