To get back to this subject. I'm happy that these modern, super cheap Windows tablets are good enough for JT modes. Mine was £49 and is about as low-spec as you can go. 1GB RAM, 16GB Flash and Win8. The important point is it has quite a fast CPU, an Atom Z3735F. It has no difficult running WSJT-X and decoding in the 12sec window after TX stops.
In addition to the tablet, I needed a USB sound card. These tablets all use the same design and the sound input hardware is not suitable for WSJT-X. 48kHz sampling is needed. I bought a USB soundcard which was £0.99 inc P&P from China and works fine. Also a USB OTG cable is needed to connect the USB soundcard to the tablet. This was £1.50, I plan to use 30m with FT817 for some data mode operations but also try 80m. For that I have resurrected my NJ-QRP PSK Warbler 80 radio that runs about 2W on 3.58MHz. I've still to concoct an antenna for 80m, I'm not decided yet on what to use.
This picture shows the hardware, PSK Warbler, tablet, finger dobber, USB sound card and OTG cable. The radio will be in a box in a few days from now.
I'll be taking this out a bit later in the year when there is more light and hence time available on a summit for experimenting. The only problem I see is getting the time set accurately. Experiments suggest the clock is accurate enough if it is synchronised before setting off. The drift whilst the tablet is sleeping for a few hours before being needed is acceptable.