Hope it keeps my layout - a review by the Geological Survey of WA (only those models they have tried) - inbuilt GPS and significant field data capabilities are what they need, including for long periods walking in difficult terrain away from a vehicle, with no battery re-charge for many hours, continually recording major data including graphical data - cost is less of an issue, so they use Motion J3500 tablets at present. Average 4x4 tourers probably only want to display existing maps (less memory and GIS capabilities needed), charge in the car, have a separate GPS to feed in location, enter no or little data. Horses for courses.
Headings for the following are (1) BRAND & MODEL (2) SCREEN SIZE, (3) OUTDOOR VISIBILITY, (4) ROBUSTNESS, (5) RAM (Gb), (6) PEN/GPS/ BLUETOOTH (Y/N), (7) GIS SOFTWARE LIMITATIONS, (8) $ PRICE (last year). I've ignored battery life but the pricey ones are 3.5 - 10 hours. "GIS limitations" relate to advanced input for detailed mapping (eg drawing freehand on screen etc)
(1) (2) (3) (4) (5) (6) (7) (8)
Motion J3500 12" V Good Rugged/dust protected 3-4 Y/Y/Y N from 3100
Motion F5v 0" V Good Rugged/dust protected 1-4 Y/Y/Y N from 3300
Fujitsu ST6012 12" Good Semi-rugged 1-8 Y/N/Y N from 1500
Fujitsu P1610 9" Good Not ruggedized 1 Y/N/Y N ?
IPAD(3) cellular 10" Mod-Good Not ruggedized 1 Y/Y/Y Y from 679
Budget laptops 10-16" mainly POOR Not ruggedized 1-4 N/N/YorN Y 350-600
Smartphones 4-5" Variable not to poorly ruggedized variable Y/Y/Y Y from 150
There are many others (Xplore Technology tablets have been mentioned at top of the range). For significant data entry with the pen-capable models, the on-screen Fitaly keyboard or similar can be used.
Personally I think a Smartphone with a large screen takes a lot of beating - cheap, fairly advanced and inexpensive GIS software is becoming available including that utilising maps most used by recreational four wheel-drivers, if you know how you can enter any map of your own, some limited data input is possible by hand (it takes more time and is cumbersome), or from a laptop at night, there is an inbuilt GPS, screens are easy to shield from sunlight because small, although not rugged they are easily protected, data can be downloaded including "track" and waypoint data and incorporated into more complex maps externally. They can even be used as a compass and now to determine strike and dip (inclination of rock orientations) for geologists using their inbuilt vertical and horizontal (3D) position, like GPS independednt of need for a phone signal. And no complex or expensive holders are needed (I use 1.5 cm of heavy-duty velcro and have never had one become detached on a rough track). Data can be transmitted rapidly home whenever one gets into 3G range for a rural handset.