tdinut,
Brucek offers wise thoughts on the idea of an upgrade. I stand with him in his view. It turns out, however, that I let go of my 4BSST2 around two days ago.
I would certainly have kept it forever. It never failed me. I loved it. Everyone who listened to it did, too.
One reason I changed to a 4B3 model is because I found myself in a position to do so (pockets were temporarily a little more ching-a-ling-y), but the true reason for my change relates to what Rod_S mentions--looks. Like Rod_S, I much prefer the 4BSST2 faceplate to that of the 4B3. When I saw the 4B3, I remember thinking that there would have to be something substantial (e.g., noticeable to a non-audiophile/non-gear-centric person/etc.) to the performance of the 4B3 over the 4BSST2 for me to make a switch, as I found 4B3's faceplate mighty unattractive.
But then I saw the 4B3 Pro model. Its clean, rack-mountable face was a fine sight to behold (to me, at least), and it turned my head away from the 4BSST2. 4B3 Pro’s face, along with the few extra pennies I had around, were sufficient to entice me into abandoning my 4BSST2. Looks–not specifications–were my undoing.
I still can't believe it. It'll be bread and water on my grocery list for a while, but with a face like 4B3 Pro's . . . . well, I just had to do it.
Falling for a pretty face is an old story. I wasn’t strong enough to resist.
Your resistance to upgrade temptation may vary.
Ilkatze
http://bryston.com/products/power_amps/4B-3-PRO.html