Goober Loc: Southeastern PA

I have the Sidekick I use with my Sony 400 2.8 and converters and it works just fine. I decided on the Sidekick over a standard gimbal primarily for travel when I am shooting wildlife and landscape. It attaches to the ballhead simply and quickly and prevents having to switch tripod heads in the field which is a pain in the butt. Also a little less weight when traveling.
The movements are smooth and precise but panning depends on the quality of your ballhead.
The only thing I am not crazy about is the side mount for the lens foot as opposed to a bottom mount like most gimbal heads use. Just need to be a little more careful when mounting the camera/lens to it.
If I knew that I would be using only a super telephoto and didn’t need a ballhead then I would prefer a gimbal head.
The quality of the locking mechanisms on your ballhead is important when hiking around with your rig over your shoulder so your camera/lens assembly doesn’t flop around due to the weight. My original ballhead was a little too small to prevent this so I bought a bigger ballhead which solved the problem.
For my purposes the Sidekick works quite well.

tcthome Loc: NJ

https://www.youtube.com/watch?v=XU_gAV5rLuk Check this out. He has a couple of vids on them. To me it makes sence. I'll probably purchase a new tripod in the next couple of weeks & am thinking of trying the fluid head. Not as compact & do not know about the weight as far as packing in on hikes.

Rdphoto3 Loc: Crossville, Tn

Very Interesting concept using a Fluid Head like a Gimbal.

Vince68 Loc: Wappingers Falls, NY

According to the Acratech website the GP ballhead can be used as a gimbal, which you already know. But the website also said it can be used as a gimbal with lenses from 100-400mm, and you said you are using the GP as a gimbal with the Nikon 200-500mm, which might exceed the limits of the GP ballhead.

I have 2 Acratech ballheads and I like them, but I am also not using them as a gimbal though. Using the 200-500mm on the GP as a gimbal may be what is causing the shake you said you have now.

Rdphoto3 Loc: Crossville, Tn

I think Acratech should have spec'ed it as a weight and not the mm. The shake I get is when I use the Head as normal and not in Gimbal Mode. I think my Tripod/Head Combo is slightly too light duty and might be one problem.