Anybody got a B10 yet? I received mine on Saturday and I'm pretty impressed. It's incredibly small and light compared to the B1/B1X and I really like the fact that the stand adapter can be removed. Without the stand adapter it can be mounted on a tripod plate so it's very easy to attach to a monopod for an assistant to carry.
I'm not sure that it's going to be able to handle the RFi modifiers especially the larger (heavier) ones over a long period of time. The tilt-lock knob is small and smooth so I would worry about over-tightening it to accommodate the weight and then not be able to loosen it again. I think the unit is ideal for small to medium umbrellas and all the OCF modifiers though.
The light itself is similar to that produced by the B1/B1X and, although it's rated at 250Ws, it's been measured to produce just one-half stop less light than the B1X (see here). I think the video light eats up the battery but can be used while on charge. I will be getting a spare battery though.
I think it will be great for weddings and outdoor events and assistants will love it as much as photographers!