Looked the rubber bumper is part of the shock dampening system!!. The top of the shock hits the damper and gives it that "rubberized road feel". Honda should come out with a rubber bumper like a Superbrace that comes in 2 pieces. Just screw a new one on every 500 miles or so, then hit the next rest area. Parts Dept. will sell 'em with 500 to the case.
OR.....Max says the travel of the shock is 53mm and the bumper takes up 60% of that travel. Maybe the bumper compresses to about 59% of that amount. I'd get the 4 year extended warranty on that bumper......OR.....Honda is going to get real pissed if they have to pay to replace that sucker every so often under warranty if it wears out prematurely. If what I saw had 300 miles on it, that piece might not last too long.