I simply dont have faith in something that my weight in a given situation is supposed to be supported by that isnt integral to the frame. Some you gents may in fact have no problem, but, i also weigh 260 lbs. Granted, most of the time, most of your weight is on the seat, bars and perhaps the tank in emergency stops, but ive ridden out of situations where ive had to "stand" on a peg (ie over large unavoidable debris, etc) at speed, and i simply wouldnt want to have the concern of whether or not a peg was going to hold up, coupled with all the other simultaneous computations going on in your brain at the time. Yeah, they may work well for a track bike, but its a track bike, on a track, with generally clean tarmac under and in front of them.
It is indeed your bike, and your body at risk, and i may be way off base, but i would consider finding an alternative were it my bike. Its not even so much that clamp that concerns me as much as the bolts holding it. Take a look at your stocker peg bolts, and im sure you'll find they are twice, or better, the size of those things. Doesnt take much to shear a bolt of that size. Again, just my .02. Dont like to see any of our bretheren hurt. I have the same fear on cast brackets like those of the RAASK set ups. Its pot metal.