Originally Posted by 7 strings of hate
The 50w gives you more headroom, so the low end is going to be a bit tighter. The big benefit, though, is the extra channel. I like being able to dedicate one channel to lead, which is why I would never stay satisfied with a two channel amp. Also, the third channel has the more aggressive presence control, so you can get more grind out of the amp.
From a tonal standpoint, though, the Dual is my least favorite Recto. The Rectoverb has more of that liquidy smooth feel, and the Triple has the gut punch bottom end and amazing clarity. The Dual is still a great amp, but it usually leaves me pining for one of the others. Which, incidentally, is why I bought a Roadster. Like Mike said, it is more like having it all.