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I have this gimbal head and I love it. I actually got rid of the Wimberly because I like this head better.
That being said, I have not used a lens as small as the 100-400 on it. I have used two lenses on this head, a Canon 500mm and a Sigma 300-800 mm lens on it. For both of those lenses it is great.
I have a 70-200 2.8 IS V2 and a Canon 400mm 5.6 lenses (referenced due to similar size as your lens). I have not used either of these lenses on this head and the tripod I use that head on. I, use these lenses on a ballhead, but you know, the truth be told, I like the gimbal head better than the motion/balance with the ballhead and maybe should try them on the MF Gimbal. Usually, both those lenses are shot hand held anyway.
The one main thing I don't like about the 393 gimbal is that the spin or rotation is cumbersome to change in the field. It uses an allan head screw, which in my opinion should be replaced with a manual permanently installed knob. If you don't get any other replies, PM me and I'll get out my 400mm and try it on this head and let you know what I think.