I had always assumed that the higher blade tip speed the better it was for a finish job. I based this on the fact that my ZD28 mower has a BTS of about 18,000 fps. And these are small blades. Take this into account and then look at the Rhino rotary cutters. The GR84 has a BTS of only 9900 fps. But it has a cutting capacity up to 4 1/2", has a Cat II/III hitch, requires at least 60hp, weighs over 2,000 lbs., and is considered "super-duty". To compare apples to apples, the Rhino SE7 (84") has a cutting capacity of 1", weighs 1000#, and has a BTS of 14,024 fps. On the other hand the Woods BB8400 has a cutting capacity of 4" and a BTS of 16,000 fps.

Clearly things are not so simple. I don't think you can look at the BTS as a stat on its own. It is something to take into account when looking at the whole picture. It may be considered, for what it's worth, when comparing rotary cutters that are nearly the same size, weight, and have the same size blades. But it doesn't tell the whole story.
I do know, however, that if you have a very heavy blade mowing very fast the kinetic energy is going to be higher and it will pulverize anything you run over! (K.E.=1/2 mv^2). So I guess if you wanted the most destruction that would be what to look for.
