I must be considered as a GPS 'newbie' and found myself in the same place as you last year before the GBU tour but learning fast..........ish.
I had my Toughbook loaded with mapping software, Memory Map or Viewranger I cannot recall which as use was limited by me forgetting the car charger but suffice to say the screen size was good but, I also found the Toughbook is a bit 'clunky' and I wanted a more elegant solution, so I went the tablet route.
It was to be just for mapping off road, and would spend most of its life in the glove box, so a top of the line tablet would not be needed. Research of my own and with advice from forum members I came up with what seems to me the perfect combination.
Samsung Galaxy Tablet SM T561 (Android)
This has built in GPS, micro sd card slot and a SIM card slot, and of course the usual Wi-Fi. Note that VR now have an add on that uses a IIRC gyroscope? You point the phone or tablet at a mountain range, and it gives you the name of said range along with height and location details.
I tried a couple of different brands of mapping software and found myself having to make a choice between Memory Map or Viewranger. Memory Map had a great offer of a map set for Off Roaders in Spain, living in Spain I thought what a result!
I paid for the download but kept getting errors when starting the download, I tried over and over thinking it was me not being familiar with the software, keep in mind I am an ex IT Lecturer, I gave in and contacted customer support, the reply was not favourable "sorry sir that map set is no longer available". I countered with "but you accepted my payment and it us still being advertised?". 'Er yes.........".
I insisted on a refund which they could not do from the UK. But I 'purchased' from the UK site, ah yes was the reply, but your payment goes to our USA office WTF?
It was not the easiest route to negotiate with the UK office having to confirm to the USA office and then, and then.....you get the picture.
Needless to say I was not impressed, when I last checked and AFAIK they STILL advertise Spanish Off Road maps! Bring on 'bad taste in mouth' syndrome, got my refund and not looked back.
So Viewranger it was, getting your head around the terminology takes a little getting used to but allow for my ageing grey matter. And something like changing the co ordinate 'type' is not as simple as it appears. But I persevered and recently sent maps with completed trails to
@Mblinko and
@froggy Steve and there appears to be no problems.
Perhaps the single best thing I like about Viewranger is the map tile purchase system. You download a country for example Spain, this is free and quite navigable, if you want a real close up you can purchase 'tiles' that only cover the area/route you want to explore, the prices are very sensible. This is great, no big pay out for a close up of the entire country, if you get a tablet that has a SIM you can download via your data plan as well as the usual WiFi. I chose a SIM that has a fixed monthly payment of 5 euro's to keep the card, or pay 14 plus vat for 30 min talk time and 2gb of data. Spanish prices are not as competitive as UK so I have no doubt you could better that,
Something else, choose a SIM with a different network to the one you have with at present, note I said network and not company. Some companies share the same network infrastructure, having access to two different networks broadens your chance of getting a signal if you need to download maps or more importantly make an emergency phone call if your normal mobile has no signal or is broken etc. The antenna in tablets is larger and I often see a better signal on that compared to my mobile phone, and of course VR software allows it's software to be downloaded to your mobile as well as your tablet, IIRC it can be used on four different devices simultaneously, so any maps purchased on one device appears on all four!
As an aside I also have a Glonass GPS (Russian satellites) but not seen much advantage over the normal American GPS most of us use.
Regards
Dave