Hi mate - I've got one and am very happy with it so far. Have only used it twice on site TFX's, but they easily outshoot a gravity fed hopper, and I didn't get a feed problem on either day I was using it. Haven't had a chance to test it with my automag yet, but according to Warpig the feed performance was about the same as a 12 volt revy (without the fancy circuit boards), so I'm confident it will be alright for my level of play. I'm using it in the North v South so if you're interested I'll mail you with an update!
It holds loads, isn't unduly noisy and doesn't throw off your aim when it "shakes". It seems large, but I've only had two hopper hits in two days of play, so that seems about average to me. Also isn't harsh on 9 volt batteries either - my first one is still going strong. No ball breaks in the hopper or feed neck so far.
However - it arrives without any documentation, and the build quality isn't the best. I had to sand and file the battery compartment and door like a b*****d before it would close properly with the battery in it. Plus, the kit snobs hate it and give you stick, but who cares what they think.