I shoot primarily with a 7D w/grip and a 400mm f4 DO with and without a 1.4x converter. Up until now, I've been using a Wimberley WH-200 gimbal head for those times when I didn't want to hand-hold the lens/camera. While it has worked great, it seemed like over-kill for my lightweight camera/lens combination and it was a tad heavy. About a week ago I decided to order a Mongoose 3.6 which arrived this morning.
It's really a superb piece of engineering and less than half the weight of the Wimberley. However, one of the first things I noticed about the Mongoose was that, unlike the Wimberley, I could not achieve a vertical shooting angle. In fact, I could only achieve about a 30 degree angle off of vertical.