I also have the Abacus A380 and have found that the supplied FMC isn't really worth using. What I've done (which seems to work well) is to alias the Ken Mitchell A340 panel to it, and then add the Mirage Works FMC (both freeware) which to me gives a better experience. Ken's panel is to me a distinct improvement on Abacus'.
Also beware the Abacus FDE; you'll need to adjust the take-off trim to get it airborne.
