@wmd: So far no issues, but my last experience are quite some years old:
From Berlin to Zurich in 2010 or 2011 worked flawless. Can't remember any details anymore, probably because it caused no issue. (No more sure which operator. ICN stopped in 2009)
Talgo from Zurich to Barcelona (IIRC 2009, definitely before 2012): The space between the opposite beds was so narrow that I had to put up the folded Brompton in parallel to the beds instead of the expected orientation parallel to the window.