My Vertax Pixel D12 grip arrived this morning. It has managed to avoid customs, yay!
Just had a quick try out. With 8 AA batteries installed, the 6fps sounds good enough for me in DX mode, what little I'll use it. Maybe when I'm desperately trying to shoot some birds in flight, a weakness of mine.
Anyway, what I did buy it for was the extra chunkiness, the longer grip down the side in portrait orientation for portraits ... and the extended battery life of course.
How does it feel? Pretty decent. The rubber bits are actually rubber, not shiney plastic like the old one I had for the D90, that was horrible to hold.
It feels solid enough, but ... I feel a very slight twitch when I move it about. And the left side [from the back] isn't exactly flush with the body.
http://imgur.com/a/k41JX#0
Don't worry, the link only leads to a mini album of pics I took of the grip, on imgur, nothing more.
Second image shows the little gap I get when it's tightened up, to the left of the OK button. Looks bigger, obviously, this close in, but it is there. In image #5 you see it from a normal distance, as you look at the back of the camera. Not as noticeable, but once you know it's there ... And I think that is the cause of the tiny rattle I feel when I switch it around from landscape to portrait. It certainly doesn't feel unsafe, as you can see, I was confident enough to hold it upside down with the 24-70 attached. It actually feels really solid, I would be confident enough to attach it to a tripod with a heavy lens on. It is that solid. That minor niggle with the tiny gap will irritate me though, I just know it.
I'll give it a more thorough testing later, attach it to the tripod etc ..