The only major (perhaps stopper) problem I see for the maps is when you use custom media.
FPS Creator X10 does not have great documentation (either did the original) on how to import your models or create models for it.
If you are using all original media (nothing downloaded) when you load the map up in FPS Creator X10 everything should work.
There are a few considerations that I can think of right now such as Waypoints do not work the same way anymore for enemies.
So again, if it is all original media, your map should load up correctly as all media from the original FPS Creator has been brought (or looks like it) to FPS Creator X10. There have been some changes to the media such as X10 only object, but I do not know how the loading process works.
If you really want to know, you can ask TGC themselves and they will give your the correct answer.
http://www.thegamecreators.com/?m=contact_orders