In reply to Grabber McFist: I've got two lensmates, the custom grip and the hotshoe cover, but not the cable grip. All are made to a very high standard and Richard is very good to deal with.
He noticed I'd very slightly overpaid him and voluntarily got in touch to tell me and chucked in the hotshoe cover to make up the difference. A basic standard of honesty, you might think, but he could easily have got away with not telling me.
The hotshoe cover is, well, a hotshoe cover. Not much to say about it specifically except it goes on and stays on.
I'd recommend the custom grip. It really makes the camera a lot nicer to handle. I haven't really used the lensmates in anger yet (still haven't got round to buying the wide angle adapter they were originally for).