I am watching this mirrorless thread with interest (http://www.ukclimbing.com/forums/t.php?n=527869&v=1) but am also wondering how things currently stand in the high-end compact market? I sometimes take a Lumix LX-3 on the hill when I'm feeling lazy, but am not very happy with the performance at anything other than ISO 100. I'm thinking of a replacement - maybe mirrorless APC (but would prefer more compact lens options), maybe another compact.
In reply to siwithington: I've just chopped in my EOS20D and lenses for a G1X. Early days yet but pleased with image quality and especially high ISO (marked step up in quality from my 20D).
Got fed up of carrying around all the DLSR gear but the G1X is the first compact that I felt could rival the IQ and warrent a switch. Mainly a travel camera so good walkanout lens (28-112mm) but it was the large sensor that sold it for me.