I found our 1935 (restored) Gibson Jumbo to be a really good bluegrass guitar -- I often will now choose it instead of our 1935 D-28. The only other old Gibson that I ever found in this class was an old AJ.
Most (not restored) Jumbos are just too raw for good bluegrass rhythm.
If you get to play guitar in wide open traditional bluegrass, then you know the rhythm role is essentially aerobic. You also know that to tell how well a guitar will sound, you must judge it in context. So comparing the guitars by themselves really won't tell you much unless you are very experienced. Nonetheless, here is a
comparison of the Jumbo to the Queen of Bluegrass Rhythm, a 1935 D-28.
Let's pick,
-Tom