R'Man;
I think the big thing here is the breeches being fit to the same frame start out the same size. the taper of the OD is very similar, in fact they same forend fits. Its sort of like you took all the metal of that last 4" from the original 30" set & spread over the front half of the 26" set. As such there is just very little difference in the feel of the gun with either bbl.
One thing I could do I suppose is to check it with each barrel on for the balance point. I realize this does not give the same results as your machine, but might tell a little bit.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra