Just fly the Free P51 for a trainer? Or even the 25T? I'm a newbie with DCS, my 1st module was the KA50. I'm glad I went for a module that could deliver combat etc, If I want to fly I can, if I want to shoot stuff I can. I would also bear in mind that you learn what you have, I had no trouble with the KA50 in terms of trim etc as it was the only module I played, so I just picked it up. Of course I'm still learning things but that's part of the joy, im getting plenty out of it, I'm only just using AI wingmen and the datalink properly (which is helping with the dumb AI :D).
In the recent sales I also picked up FC3, A10C and the MIG 21.
The FC3 A/C are not easy, I agree they don't have the same depth in terms of systems etc but that means you have more time to concentrate on aspects such as weapon deployment, ingress, egress etc.
Myself I don't really see what the Hawk and similar training planes offer, at the moment they are SFM (although they will be improved :D) and they are quite expensive, you can fly the P51 all day and its good fun. After getting some flying in I can see your friends buying a new module to shoot stuff....
OFC I might love the Hawk etc if I tried them, but I cant see appeal atm, especially with the Sabre and the MIG 15 being just around the corner, which seem similar in capability.