I agree, from reading the forum threads regarding Classics & Classic DX's and other S&W literature I found in catalogs and online, I would say that these 2 model 29-5 versions are pretty much identical to each other besides extras you mention that came with DX.

According to '91 S&W catalog both models have all the same performance enhancing features like target hammer, target trigger, full lug barrel, drilled & tapped for scope mount, etc and both versions had other enhancements such as "internal endurance package and accurizing package for competition-ready group sizes."

With the exception of Classic DX on barrel and the extras that the DX came with, both versions probably are capable of shooting 2" or better groups at 50yds-
I'm am not 100% certain, but I think only the DX came with a factory test target as proof of performance.