Hello,
I had a chance to test the SLR as a frend just bought one to be parked in his garage with a "Gullwing".
This is not a good car as it suffers from instability at top speed, the chassis is not good.
The power is here but with auto trans. In fact the pleasure is taken by this antisportive system.
It's a very nice car but for less than 50% you can buy a CL65 AMG with 612 PS which offers the same power and a better stability.
To coclude : the MacLaren / BMW F1 doesn't have to worry and the GT also !