I was wondering if products like RIO Carbon, Forge, Cali, Chiba or Nitrus were able (with their latest firmaware, of course) to do gapless playback like RIO Karma, this would be interesting beacause gapless playback to me is one of the most important features for the music I listen to...
Thanks for answers

Unfortunately, only the Karma has gapless playback support AFAIK.

Here is an interesting thread:
http://forums-riovolution.com/index.php?showtopic=8137&