That's actually really useful to hear, and I'm so glad you've enjoyed your C63S.
The E63S was ridiculous, as I suspected it would be. It put a smile on my face the moment I started it up. That engine is pornographic. The ride, even in comfort, was arguably the wrong side of 'firm' for a family car, but I can probably live with that. I had a decent 30 minutes in it hooning around St. Albans, both on open roads and in some heavy traffic on residential streets, so it gave me a decent idea of how it would perform across a range of roads.
Fundamentally I know it's a stupid option - it will drink petrol, cost more to insure, will be less comfortable for passengers, and I'll rarely have the opportunity to probably unleash it - but is very, very tempting. And as you say, you only live once - I had enough near misses in Afghanistan to appreciate that!
I can't shake the feeling that I would be constantly on edge that my children or dog would scratch / stain / throw up over it though - that it's almost too nice a car to be used to ship them around, or drive to the beach / park / rugby club etc. But then I think how much fun it would be to take the wife away for a long weekend of walking in Wales or the Lakes, and give the car some tap in the process. The 540i would be a much more sensible option, and is still good fun to drive, albeit not in the same league as the E63S. Argh, decisions! The E53 would have been perfect I think (sitting somewhere in between), but that ship is sailed.
I'm going to sleep on it and then decide tomorrow! If anyone has any final views on the usability of an E63S as a family car, (e.g. ride on UK roads, and is the fuel economy really that atrocious?), let me know!
I used to be someone who was concerned about prospective car damage but having not allowed that to rule my choice of car, over the years I've learnt to accept that whatever you buy is probably going to be damaged from a number of different sources but you can always get it fixed.
It doesn't change what car you are in and the fact you get to enjoy it all the time which far outweighs the pain of having a compromise or even crap car that you don't really want (which would potentially still need to be repaired / cleaned etc.).
I've got the most expensive car I've ever owned and yet we use it as much as possible - including eating in it when the need arises. There was a time many years ago I tried to avoid using my cars but you are only here once so make the most of it. It's got a few bumps here and there but I couldn't care less! I will get them fix when the need arises but most people wouldn't be able to see them anyway. It's only close up and most cars have similar in any case.
I still enjoy driving it as much as I always have done.
MPG won't be great obviously with an AMG but my honest view is that although they are obviously worse, they are not that much worse than most moderately-sized petrols... especially if you aren't doing huge mileage.
Having had an E55K in the past and sometimes getting early-teens MPG, it really boils down to are you happy with the amount you spend on fuel vs. the enjoyment you get out of it. If you are then don't think about it.
When that balances changes and you are no longer enjoying it enough to warrant the cost, it's time for a change...