The one you have linked to is the same ladder different seller that I have linked too. Mine is rated to 330lbs, as are all the ones I have seen.
I am 250lbs myself and I have gone up and down the ladder many times with no failures. The more vertical the ladder is the more secure it feels the climb. Also, if you don't need the full 12.5' that too helps the feeling of the ladder.
That said I have fully extended the ladder and climbed up many times. Although there was flex in the ladder it has held. I wouldn't want this ladder if I was using it daily at its full reach, but for us to sweep of the slide and occasionally check the roof it has been great.