My new 550 is charged and in business. Really quiet compared to my older Roombas and seems to do a better job of "learning" the area its cleaning. Another nice feature: it slows down right before it bumps into walls, furniture, etc. Touches them really softly before changing direction. Nice!
The new Dirt Dog is in the garage doing a great job with the rough stuff. It didn't come with a docking charger, but I used one from an older Roomba and it worked great. Not bad for $120
Dave - I haven't heard anything first hand about the Scoomba. Wonder if it works well?