Thanks folks. I figured the Kurzweil might be the more accomplished unit due to their general reputation for pianos. There are very few around here in the UK however so I might end up with a nanopiano anyway!

I have found a UK magazine review of the nano which is pretty upbeat but I haven't tracked down anything similar for the Kurzweil. I have found user reviews of both of these units but as ever they veer from adulation to desparation.

I suppose like all other audio it's a very subjective matter but if I go for the piano module option then I may well have to buy without audition via mail.