Re: "I don't agree with the author that it has to work with the old ESP framework"
While I agree it would be beneficial to be able to import the old models, if you've ever tried to work with .air files describing the flight behaviour of the aircraft you'll know it's a pain. By the time of FS2004 and FSX even MS/Aces Studios couldn't quite figure out what each parameter was supposed to do and how it interacted with the simulator framework (As witnessed by the abysmal flight characteristics of the default 747 for instance).
Many of the add-ons (especially the more extensive ones) were broken between the original FS series as well and required a lot of rework often requiring repurchasing. I don't think this would stop uptake of the new version if it offered enough of an upgrade to do so.
A better (and more real world units based) flight model could go a long way towards that.
Biting the hand that feeds IT
