I've been using the Solid FX8 for a month now and like it very much.
Are you using it with the US plates, or with Jepp plates?
If the latter, what is the update process? Does it involve a PC, or does the Kindle download the data directly and if so, how? Does the download website just deliver the paid-for coverage, or do you enter coverage codes like in the PC version?
I think the FX8 hardware is actually made by Irex, and a while ago I knew exactly but cannot find it right now.
I used to have the Irex Iliad but it is long gone. The stupid buttons which their PDF reader had on the bottom of every page reduced the area available to display the typical approach plate in the worst possible way, to a level where I needed glasses to read it
There was a replacement PDF reader around but one could not install any software on the Iliad (which was basically an ARM based unix platform) without a special code obtained from Irex and this was too much hassle.