I tried AFPex last month - two IFR flightplans at low-level across 3 countries in europe. Weather and tech problems meant we had to make changes and delays - this was a nightmare. We usually print the ACK message and carry that in the aircraft but I (eventually) found that AFPex requires you type in field numbers to make changes
There is also no list of your flightplans that you can pick from.
Impractical and obscure; I've gone straight back to homebriefing which is, IMNSHO, well designed and user friendly. Worth the cost.
A private Kingair driver of my acquaintance didn't get as far as actually filing a flightplan before rushing back to the Austrian offering.