The more I look, the more I think that I will end up with an auto to get the spec that I want - I also think that for the majority of the time, it will be the right choice.
In the real world, I don't think the gear change on an auto feels faster than a manual (unless your the Stig). The manual box on my 325 has a long throw and isn't that fast to use. I drove my uncle's 735 and X5 and the auto box in them felt pretty good. The box on the 540 seems to shift well and the acceleration is relentless and without interuption. I think I really need to go and drive both and see what I think....
I'm not too fussed about tuning potential - I won't go beyond a good induction kit, maybe a remap and some lowering springs.
If my heart wins, it'll be an early E46 M3 - which I'm sure will end up in a whole world of financial pain. Which is why I won't test one - just in case!