Well, I guess developers have studied the IXEG 737 well by now and got *inspiration* in many areas
As for the new default 737NG, I believe Alex is behind the 3D on that, and he is possibly the best 3D designer in X-Plane, so I expect that to be awesome. The MD80 is most likely Sergio Santagada's which has existed behind the scenes for a decade but never got released, and I'm really happy to see it again in such good shape! For those who are not old enough, Sergio is kind of the "Godfather" of XP, he built the first quality airliners in XP and played a major role in XP development of scenery, aircraft and textures in the period XP v5 - 9 if I recall correct.