Size and weight always kept me away from typical gimbals. I then discovered the Wimberley MH-100 MonoGimbal and it was perfect for my needs: definitely lightweight, easy to use on a monopod (I prefer monopods for long lens shootings) and if required could aloso be used on a tripod with an additional rotating plate. Should be a big and heavy tripod, though, since the lens is mounted on the side of the gimbal, so could potentially drag the whole tripod setup sideways.
Editor
opticallimits.com
opticallimits.com