Good debate guys. I have to vouch for Racer on this one - I was there when they tested the box on the 70 and it made no difference whatsoever. The brother men are very similar in height, weight and riding ability and they did indeed switch riders as mentioned in the quote. Actually, it was all done fairly scientifically (obsessively perhaps? heh) with wind speed, fuel weight, terrain, individual engine performance, and body mods taken into consideration.
Then again, the test was done on a '70, not on a '50 as HSB's test was so who knows - maybe such a mod would indeed make a 50, almost literally, fly. 70 (seventy) ft/s is however, quite unbelievable. If it's true then, wow.
Sounds like good advice to me.