"Singing sustain quality"... I like that. Very appropriate. Beep.click and Eugenedunn, you mentioned volume? The Twin is cleaner (it just doesn't break up) but not really that much louder. Last week I had my BFPR out at an outdoor show, in a town-square sort of setting but with several hundred hundred people and lots of open air. The sound guy gave me a choice - run the amp at 7 or send it through the board at 3. The band asked me to go through the board because they were having a hard time hearing their monitors, so I did. There was NO lack of volume.