To be honest... 2.5 is what I always wanted in the past when I was playing DCS 1.2.x, but it's actually better!
I never imagined that DCS would look like the way it is now, never. Not sure how it can get any better. From the terrain to the visual effects, everything looks great. Especially the PBR and deferred shading.
Is it missing things? Yes but it's getting there! It's getting better.
Yes, the Viper definitely has a better TWR and it can maintain a constant turn rate very well. Tho the Hornet can pull a lot of AoA, it bleeds energy quite fast.
It's not really Power to weight ratio Kev2go. You are talking about jets, so it's 'thrust' and not 'power'. Power is related to horsepower, work rate, thrust is described as a pushing force, a jet engine produces a force, not power.
Please see what Cunctator said above; "Will this be a general engine improvement".
Example: Cooling system. New technologies being developed for the Yak-52 could be applied to older modules in order to make them more accurate or improve the existing features.