I had the same dilemma. I decided that if I wired up the Fox to the Humax portal (or better still the custom one) I could get iPlayer etc etc, and that this would give me most of the Youview features on a tried and tested platform.
Mine was £150 from XSItems on Ebay, ex-display but as far as I can see unmarked and fabulous.
I'm leaning towards getting the FOX as well. If its easy enough to set up I player, etc on it then that would be a bonus.
I might just hold off for a month or two and see what happens with prices with existing humax products and new youview boxes. Hopefully they might drop in price and have better features.