Okay, I think I see your point, especially with the 700 version.
I have experienced the same energy issues with the 37-7 and up...these guys are really slick compared to previous variants.
You can note a significant difference in the wing design, especially the inboard flaps.
and yes, Boeing buried the differences. It became very apparent with RNP-AR procedures, having the design/performance parameters for an "NG", the 37-7 winglet and 37-8 variants had quite a bit of trouble with the many of the tighter turns to final.
A good example was one of the first RNP-AR designs, PSP. The variants could not make that final turn, and eventually, the ASA procedure was abandoned.
Boeing, for the longest time, has tried to keep the 737-NG as a blind NG for access, trying to keep the 'NG' as a CAT C as long as they can...this makes it difficult in many ways, especially the 140kts FAS...
I did not have the same issues with the Airbus aircraft, the data provided has always been much better for design purposes...