Be aware that the 747X is heavily custom-coded while FDC is aimed at reading data from the FSX SDK.
So FDC does NOT have much of a chance to read the position of every knob and switch on your 747X to tell you whether you should act or not.
For a custom-coded copilot you should have a look at the taylor-made FS2Crew version (much more complex, though, and "locked" to a single aircraft).
Having said this, I like my FDC a lot:
- You can run your checklists. Not every single item will be interactive, but the full list is there and you can check the knobs and switches for yourself.
- You get the performance file which tells you when to raise or lower the next notch of flaps (kind of stall protection!)
- Lots of options to configure. Be prepared to develop your own set of checklists, just as rw airlines would develop their own ones from the "template" provided from Boeing!
On the Aerosoft product page, there's a pdf manual freely available for download so you have a chance to check FDC against others before you buy (FS2Crew, MultiCrewEnvironment, for example).
Feel free to come back here and ask something specific. I'm biased towards FDC and have been using it for a number of years. Got this thread bookmarked, now.