Yeah, BMS is worth playing and it's great that there's an active multiplayer community as well. It's been eons since I've done Falcon multiplayer - but I'm sure I'll come around to it again! F4 has been installed on my hard drive in some form non-stop since its release in 1998, and I don't think that's ever going to change
Oh, and as to the question about sims with dynamic campaigns - honourable mentions should also go to Rowan's titles, namely MiG Alley and Battle of Britain. I'm not sure whether the former runs on modern systems (I guess I'll have to install it and find out!), but BoB lives on - as A2A Simulations' BoB II. It's a bit dated, but has a very active community that continues developing officially-approved patches. Both had true dynamic campaigns.
It's unfortunate that most simulators don't do true dynamic cam paigns, even if they claim to - in many cases, what's passed for a dynamic campaign is actually just a semi-random mission generator. IL-2 is noteworthy for that.
CFS 3 (which also has been well-maintained by the community!) is somewhere in between - it's closer to a dynamic campaign than a mission generator, but it still vastly simplifies the actual conduct of war; I'd think of it more as a sandbox. Worth mentioning too is the CFS3-based World War I title Wings over Flanders Fields - which while not "truly" dynamic does have an outstanding campaign mode. It's made all the better by a very clever AI, which (at higher realism settings) not only fights well, but also makes healthy choices for its own survival (like disengaging it finds itself at a disadvantage).
And for those who want dynamic campaigns played on a strategic level (i.e. not in a simulator game per se, but a game where you control the air war) - there are the Gary Grigsby titles "Eagle Day to Bombing the Reich", and the recent "War in the West" has some air-only campaign scenarios as well.
Not modern combat like F4 but all worth bringing up nonetheless