c6 auto transmission question

[ShortBeardy]

Very specific curiosity: How does the C6 auto compare with the ZF6HP26 transmission found in the 4.2 XKR (2007-2009).
I have an XKR and am familiar with this auto and I have read various opinions on the C6 auto, but most have no point of comparison. I am hoping someone might have some specific experience here?
thanks