I see that simbrief is used in the Acars to generate flight plans. I use Pro ATC X, which also gives me my ATC, and use many of the flight plans it generates. My question is , do I have to use the flight plan that simbrief generates, or can I just use one I program into my Q400 FMS?
SimBrief is optional, you are welcome to use your own flight planning tools :) I have no idea how realistic Pro ATC X European routing will be though, there's a lot of complicated airspace and corridor rules in Europe so if you were to use its flightplans online with VATSIM or IVAO you might run in to issues.