Try right-clicking and "save as"
As far as the rest... I have both X-Plane and Extreme Air Racing (and almost every other flight sime to come out since SWOTL) and neither has as a good a "feel" as AH. Go ahead, try a high speed snap roll, flatspin, tailslide, whatever, only AH even aproaches reality when it comes to stall behavior. As a matter of fact, I have not yet found another flight sim that will let you get into an accelerated stall by just yanking too hard on the stick. I mean, my god, did you even try the "dogfight" mode in Extreme Air Racing? It is absolutely terrible. And I wouldn't want a historical combat flight sim based off X-Plane either. Though a "fantasy" combat flight sim based off X-Plane would be fun

Dynamic Flight Modeling is modeling how your aircraft flies in real-time. Things like how gear and flaps, fuel and ammo, bugs on your wing, etc... change the handling of your aircraft. Clipping your wings before the flight starts, does not automatically qualify as a "Dynamic Flight Model". Most flight sims would simply apply a set of pre-existing conditions to model the clipped-wing effect. They would not, as you contend, figure out the appropriate conditions to apply "on the fly" in real-time. It would be much harder to develop aircraft for true dynamic flight modeling. You need to know EVERY little detail of a plane to truly re-create it properly with a DFM. Not only do you have to know where all the rivets are in a P51, you have to PUT THEM THERE in the model. This roughly equates to actually building the aircraft in terms of development time. You have to know things like the surface friction of the finish of the aircraft you are modeling. And what happens when you are all done and your "model" doesn't match the performance of the original? I guarentee few, if any, of them would.
What you are asking for is non-trivial. I for one would much rather have a finite plane set, that all handle very closely to their historical brethren, than an unlimited one that simply approximated them.
IMHO, AH has the best FM of any flight sim to date. I think many, if not most here, agree with me. Why do you want fix what ain't broke?