I would be tempted, had I not found ViewRanger about a year ago. The mapping software available includes all 1:50,000 and 1:25,000 maps, as well as European. It runs on any Nokia phone that has a GPS, or can bluetooth to a GPS node. I run it on a spare Nokia N73 linked to a Nokia GPS node (about £30), and it is superbly precise. You can download maps as you are out and about, or you can pre-download them before you set off.
The 1:50,000 pack of all the national parks, including software, is £25. As far as I can see, the only advantage of the Satmap10 is the size of the screen, but - as I found out during the 100 night-section, you can easily navigate by it.
Features in the software include recording tracks, waypointing, importing POI's and drawing the view from where you are standing.
www.viewranger.com
Garfield