FWIW, I once ran an iPad for my nav but when it came time to upgrade I went Android for two basic reasons.
First, price. Apple products demand a serious premium. If it's worth it to you or not is beside the point, but they are much more expensive.
Second, GPS (this is also price related). iPads do not come with GPS built in unless you get the version that also has cell service. And that costs more, both on the front end and because you then have to add the device to your mobile plan. The non-cellular iPads 'fake' GPS via wifi signal locations and such but it's not very accurate and is completely useless in the bush. You can work around this by using an external GPS antenna but again that's extra cost. Additionally, and more annoying, it's more cables to wrangle in the cab and I have enough keeping my tablet and both (his and hers) phones charged.
I have never felt I wanted/needed an external GPS antenna for my tablet or phone when off road. The tablet rides on the dash in both Rovers and has a pretty clear view of the sky through the windshield so signal has been good.
One worry about putting a tablet (or phone) directly in the windshield and then running/charging it full time is overheating - sitting under the glass in the full sun it can get too hot. On mine, it will stop charging if it gets too hot. It is a Samsung after all, so that's probably a good thing since I don't want to go all DreamLiner. However I have the tablet positioned right in front of an AC vent on the LR3, so as long as the air is on it stays frosty and cool. It's only when I leave it sitting in the truck on a hot day, say if I'm out stacking rocks or something and shut the truck down, that it stops charging.
One last note regarding tablets - get the biggest you can. It costs more up front but if you have the space for it you'll never regret it whereas you'll often find yourself trying to zoom in/out or trying to see a too-small icon while bouncing down a trail with a small screen. I'd consider a 10" a good size. The 7" tablets work fine sitting in your hand, but trying to read it from across the cab on a rough trail, much less actually control it.... Trust me - just go bigger if you can find the space.
As for actual software, Gaia has changed their operation to a subscription only service. I still like them as well or better than anything else I've used but that's not to say others aren't decent. We have a partnership with Gaia for NCLR members, and will be doing something with them for the National rally this summer where we will have all the event trails on the Gaia cloud for all the participants. I don't have time right now to get into software details, but the topic started with hardware so that's where I'll leave it for now.
Edited by DHappel, 02 January 2018 - 09:43 AM.