Rick: you don't need to play the monster scenarios if you don't want to, but they are fun as a change of pace - especially when you have to compete with an enemy ship.
You can get the feel of a game without destroying the streamlined mechanics of the other rules system and that's what I see as the main benefit of the partnership - streamlined rules that allow massed fleets without the nickpicking detail of SFB (I only got to glance at my FC box before packing up for the move - and 3 years on, I'm still looking in the spare room for that last (naturally) box with my RPG and gaming stuff in...). FC seems to have gone some way, but ACTA is where it's at.
But I'd say also.. don't expect the same gameplay as ACTA: B5... that was set up to represent the Babylon 5 combat scenes, just as the SF version will have to represent the SFB combat, so should have a different feel to it, just as NA and Babylon 5 probably have differing feels. Besides which, if you make all the games with the same system feel the same, nobody would buy both - they'd just buy the one and stick to it...
That having been said, I don't want to see the ACTA: SF rules get too complex - it's a nice system (I now own both ACTA: NA and VaS). The one thing I think you'll see is shields hard to get through, but once they're gone, the ships die pretty quickly - that's generally the way SFB seemed to play out, although I'm not sure how they're going to translate the directional shields from SFB which made it so tactical (nothing like having to keep your damaged shields away from an agile enemy to tax your mind...).