Jim, yesterday afternoon my daughter was singing in the church chior with the daughter of the local Branson/New Holland mechanic. He and I got to talking afterwards and he mentioned he was not impressed with the Bransons. Their dealership has only sold a few of them, he thinks only 5 since they got the brand about 6 (?) months ago. But his criticism was not based on any noise or sound, it was the rough castings, the crude ergonomics, etc. This guy is an immigrant from Sweden and said the Bransons look a lot like the old Russian/East Block tractors, stout, basic and unfinished. Now my impression of them is not nearly that bad. I agree that they have ergonomics that could be improved, but the finish didn't look that bad. I guess I didn't really look at the metal castings, I mostly looked at the operator platform. Anyway, he said that the Bransons were a lot like the old tractors from the 50's and 60's (and since so many of those are still around, that can't be such a bad thing!).
I can certainly hear the difference between the Kubota engine, it seems smooth through its entire RPM range. The little 24hp engine in my NH has a few areas where it could be smoother (lower RPMs), but as the RPMs pick up it purrs like the Kubota.
I tend to think that most any engine could be improved upon.