I just got my 7d and have been shooting a 20d for years. I have always had a battery grip on it for the vertical release and just a little more mass, it has a real Canon grip. I just cannot justify the money for a real canon grip on the 7d. I have used Opteka stuff before, I am thinking I will go with theirs unless there is a good reason not to. I do not think lens weight will be an issue with the mount, I own L zooms up to the 80-200/2.8 and sometimes rent a 300/4 IS or 400/4.5.
Ditto to the above...I have owned both the Opteka and Zeikos grips and have found them to be satisfactory in every way - and at a fraction of the price of the OEM version.
I'm using a Zeikos on a 7D as well...no problems. I had the Canon grip on another 7D and I'd say the Canon grip has slightly better build quality but IMO it's not worth the price premium. IMO there's no significant difference in feel or function...
I got a used 7D with an "Aputure." Decent fit but worked intermittently (back button wouldn't focus). Purchased the Canon. Better fit and feel but the shutter button is machine gun crazy. Will be sending it in for adjustment. In general I think OEM grips are better though they are 50% more expensive.
I've gone through 2 Zeikos grips on my 7D in 2 years. Zeikos replaced the first one that only only lasted 3 months. The second grip only lasted a bit longer. I wouldn't buy another grip from them. Go Canon.
I can only relate my own experience with the zeikos grip for my 7D, but the very first outing after putting it on my 7D I got a battery error after about an hour of shooting. The error didn't go away after removing the grip and I had to send in my body for repairs. The grip hasn't been back on the body since.
I have never had any problems with Zeikos. I had them on my D700 & D300 Nikons for several years.
On the other hand I now have a 7D that came with a Canon grip & have had it work loose several times, but other than that it works OK.
I've used detachable motor drives on film bodies in the past, but haven't used a battery grip since going digital.
I can't tell from the photos on B&H or the Zeikos home page: does the grip have its own tripod socket, or do you lose tripod capability when you attach the grip?
[Never mind: I found a YouTube video, and it shows the tripod socket.]
