I bought a SatMap a couple of years ago, great bit of kit. I've only got the northern half of the UK at 1:50k but it's all I really need. Used alongside a map and compass it works really well at confirming location when the weather comes in or the terrain starts to get tricky. They're hungry on batteries if you leave the tracking system running and navigate the maps on screen too much, but I used one set of AA lithiums on the TGO last year and used it everyday for 200 miles.
I've hardly used any of the features on it, I literally turn it on and wait for it to get a signal, confirm my position and then turn it off again. I still prefer a good old map and compass, I just like reading maps I think, but they're handy for a backup or for confirmation.
I not looked at the other alternatives sorry