I have had two of the three....Immeasureable is the smallest...it is just not as long, but has a nice depth (about 4-5 inches if I remember!) and the WU is a wonderful true feed bag type of bag...it is longer then the Immeasureable but it too has nice depth...it is a great long uninterupted expanse of crunch leather...and the detailing on the strap is wonderful (3 buckles wrapped in leather) both these straps are comfy and non-slipping.
I do not have a shopper, but know it is a LARGE bag....