interesting thread indeed. Ive owned many cyrus amps over the years and always ended up coming back to the 3. Its a solid bit of kit.
Lately though, i've been using a 3i... and genuinely dont think it deserves the bad press it gets. Having owned 3 original 3's now... with and without PSX-R's, i'd genuinely say that the 3i is not that dis-similar in sound. In fact in some ways i prefer it. It doesnt quite have the bass heft of the original 3, but the top end is a little better, and it still turns in a remarkably smooth performance. The power amp stage as far as i know is still identical to that of the original 3, it was just the preamp design that changed to bring it more up to date.
I'm going to experiment soon with adding a PSX-R to the 3i.
To give you some idea of its relative brightness... myself and a friend recently compared the 3i to an audiolab 8000S. In every case, we found the cyrus to be smoother, sweeter and more pleasant to listen to than the audiolab which tended towards brightness and upper midrange forwardness.
The only area of excel for the audiolab, was in terms of projection of midrange, hence good vocals. Stronger bass (most likely an effect of its larger current reserves and bigger power supply) and slightly wider soundstage.
It's my hope that adding a PSX-R will bring some of those elements to the 3i.