Why do you say that the IFF (INTERROGATOR) in FF5 is not realistic?! An IFF interrogator works the following way:
-> Friendly aircraft interrogated by the IFF returns a signal while enemy or even neutral aircraft don't return any signal. IFF interrogators are associated with the radar and when friendly aircraft are interrogated their simbology in the radar is changed, this is how things work in real life, period! It's not that hard to model this! This is modeled in several REALISTIC/HARDCORE combat flight sim such as F-14 Fleet Defender, Jane's F-15, Jane's F/A-18, etc... This is also how it's modeled in FF5.
It's really curious that you said that IFF in FF5 is sub-par, seeing that FF5 models an IFF interrogator and BMS does not!! I would say with 100% confidence that the IFF in BMS is one that is "sub-par" at least compared to FF5!
In fact and from reading many posts from OF/BMS fans (note that I also enjoy BMS a lot) and people like you I see that many confuse an IFF transponder system with an IFF interrogator system. The IFF interrogator system works exactly how I described above and this is the system that many players including me are asking for!
The IFF transponders uses several channels (military and civilian), codes (which BTW are configured while the aircraft is on the ground) and may have diferent modes of operation -> Honestly this isn't what I'm asking for since a "generic" IFF transponder system is enough for me.
I also find ammusing when I see someone saying that the IFF in FF5 may not be 100% realistic or that's "simplified", etc... but the fact that a simplified system like and IFF interrogator is MUCH MORE REALISTIC that having NO/NONE system at all! What I mean is that it's well known how an IFF interrogator works so having something that works like that is more realistic than not having an IFF interrogator at all!
Besides do you think that everything you have in BMS is realistic?? If yes, than you must still believe in Santa Claus or something like that! For example the "declare" AWACS command that all Falcon 4 sims (stock/FF/OF/BMS/etc...) have is much less realistic and much more simplified than the IFF interrogator in FF5 since in the real "declare" the pilot must state the position and distance of the suspected aircraft in relation to the bullseye and other necessary info! And the list goes, on and on and on...
Regarding the sounds and like I previously said, PC combat flight sims will NEVER give the same amount of feedback that real pilots get in real aircraft so PC combat flight sims must have "extra" features in order to compensate for the lack of feedback that PC simmers don't get. For example, in real aircraft you clearly feed the landing gear extending or retracting but the real sound of the landing gear is faint (even more faint when the pilot is wearing a helmet) but since in PC sim it's impossible to for example feel the landing gear this feeling must be modeled with a "bit of exageration" on the sound part! So yes, IMO the sounds in FF5 not only "looks" better in my heards but also gives the feedback that I would get in a real aircraft but I can't get in a PC (except by sound).
Fortunally you admit that GPS weapons are great and realistic in FF5 but unfortunally it seems that's only probably due to what you said, that the guy that made the GPS weapons for FreeFalcon now works with BMS! But since I'm not that "fanatic specific Falcon 4 - XX version" and I enjoy both versions (BMS and FF5) I don't let myself affect with such things...