Don't mean to pour petrol on a smoldering fire, but if you haven't experienced Manfred's "Gutersloh" in Fs9, you probably aren't able to appreciate how immersive this base and flight activity is.
First, it's based on VTOL jet aircraft, the Harrier. They are deployed from the airbase itself and also from remote, temporary "Harrier hides" tucked away in forested areas. There is AI and user controlled Harrier flight activity from the base and and the hides. Also present is a fleet of CH-47 Chinooks that you can accompany on flight sorties. The hardest part to describe is the airbase scenery detail, which, even in fs9, is incredible and vast. Remember that there is the base itself and several "hides" that are a number of miles removed from the base.
As I mentioned, there may be challenges to fully appreciating this scenery. First, you probably will want a Harrier that is equal in detail to the quality of this environment. In Fs9, I noticed that some add-on aircraft were modelled in a scale that was somewhat larger than AI aircraft in the scenery. Second, I found that another way to enjoy Manfred's amazing artistry was to have a driveable vehicle to explore all of the eye candy such as hangers, roadways, parking areas, and buildings on the base. The best I found was Hama's Unimog trucks. For some reason those are not quite as immpressive in FSX as they were in Fs9. The sound and vehicle interior files did not convert well.
All I can say is that I hope Manfred and his collaborators are willing and able to complete the conversion of RAF Gutersloh to FSX. If you like military flight simulation, this immersive cold-war scenery shows what can be done. The fact that it is freeware (historically) puts it in a class, literally, by itself.