At HE2007, I listened to two systems with Bel Canto REF1000 and S300 amps. The sound from both of these systems was a bit grainy on top. There was enough bottom slam, but it wasn't as clean and tight as some other tube and ss amps at the show. The systems were totally different for each amp, but these qualities were consistent for some reason. This finding was quite surprising to me as I was expecting the BC amps to sound clean, articulate and fast, based on impressions from reviewers and other users.
In the end, I ended up getting the Spectron M3 SE. After 5 or 6 months, I got another one and set them up in balanced mono-block configuration. I couldn't be happier with my choice.
iSanchez