The major benefit of the A-100 and other models in that range is that Panasonic designed it with the idea of being directly head-wearable. GoPros are lovely things, but for our purposes they're shite because they were designed with the assumption that you'd clip them onto a helmet or mount them on some fixed object. The Panasonics all clip into a headphone-style mount that sits next to your eye. (Other mounting options are available.) Looks like this, apologies for low-quality image.
The one drawback with the A-100 is that it's a lens on a long string, leading to a control box. Looks like this.
Which means you have to put the control box somewhere. And guess what? The string is half a metre too short to be really useful. I've had extra pockets sewn into my shorts, but if I were any taller than 5 foot 9 it simply wouldn't reach my waist and I'd have to keep the box in a somewhat awkward arm holster instead (a shirt with a top pocket would be ideal, but apparently rugby doesn't believe in shirt pockets).
There is a newer model, the HX-A1, which doesn't have the control box, but it also has massively reduced battery life that doesn't really make it feasible for us (from ~2hr 30min to ~80ish minutes at 1080p HD). You can get a screw-in extended-life battery and go back to 2hr 45-ish, but I've not tried that and I'm not entirely sure that the weight distribution would work.
Image quality with the A100 is okay but not razor sharp like you'll get on a camcorder; you'll be able to see hands on the ball at a range of 10 yards, and be able to tell whether the hands passed the ball forward or backward at 20 yards. That's all you need.
There are two different models of head mount. The original A-100 mount is rubber and plastic
and looks like this. There is a newer, quite a bit better, lightweight metal mount
that looks like this.
My personal recommendation would be to get a HX-A1 plus extended life battery, but that's just me selfishly trying to get someone else to drop money to test something (not least since I can only find the VW-BTA1 battery on eBay and grey market import sites). You'd be looking at about £200 for the lot. An A-100 will cost less than £100 on Amazon or eBay and include everything you need to start, except a microSD card (make sure it is a
microSD). 32GB is plenty for multiple games and you can have a Class 10 card for £10. Make sure you get the black, not the dayglo orange, unless you're looking to coordinate with an equally orange shirt.
A final word of warning: do
not under any circumstances buy the A-500, or "the one with the screen". You get all the disadvantages of the 100; very, very slightly improved image quality; a bunch of useless Gucci crap features that you'll never use; and you'll pay at least £150 extra for the privilege. If you feel minded to do this, you should instead get a 100 and PayPal me the difference, which I promise to use for something more useful.
edit: they produce Panasonic .MTS files, which you can play with VLC Player without needing to convert them