I agree with Sven... the slate is the most mobile, and, remember,
"hooking" includes bluetooth devices such as keyboards and mice, some
very small and convenient which can ride in a pocket until needed.
There's even a bluetooth mouse which lives in the pcmcia slot until needed.

imho, the biggest consideration for a convertible is they normally are
the only option for the inclusion of a DVD drive to allow watching
movies on the go... and, the unexpected benefit of being able to tilt
the screen back from the front edge so it works on an airliner tray.

Beverly Howard [MS MVP-Mobile Devices]