I was thinking of getting this and I wondered if anyone had any experience with it.

I'll be using it with a Panasonic GH2, and I'm particularly interested in how compatible the follow focus would be with my lenses. I have the 14mm, 20mm (Lumix) and 45mm (Olympus) primes, and the first two are very small and close to the camera body. According to the website, you're supposed to buy a gear to go on the lens (is that compulsory or just a way to get you to spend more?), but the right hand side of the GH2 body protrudes almost beyond even the 20mm and might well get in the way of the gear, which looks pretty big. I'm less concerned about the 14mm, because that's not exactly hard to get in focus anyway, but ideally, I'd like it to work with everything.

Or will any old cheap focus gear from Amazon work? For example, this? http://www.amazon.co.uk/Follow-Focus-Canon-camera-DC200/dp/B009WKR9CQ/ref=sr_1_1?ie=UTF8&qid=1387139689&sr=8-1&keywords=focus+ring

You need a gear on the lens for a geared follow focus to work.

More importantly, the Gini FF is not a good choice for small lenses and cameras. Too big with no fine tune adjustments.

Look for one that slides in and out to hit your lenses, it will fit better with a small setup.