Well, i know someone that went over 200,000 miles on the original timing belt and nothing happened. I would never tell someone to do that, it's always a risk when over 100,000 on timing belts. My father is an engineer at Honda and he changes his belts at 90,000 miles no matter how well his are driving at the time. He went 270,000 on his Accord b4 selling it and it was still purring. He has 170,000 on my mothers 01 accord v6 and it runs like most cars with 20,000 on em. He now has an 08 accord 4 banger, nice ride.

As for the timing belt being done yourself? the only thing i would suggest is to take it to a shop, or better yet, the dealer and have them loosen the main shaft bolt. Mine wouldn't come off and two shops later i had to take it to the dealer to get it off cuz the shops thought they would break it after torquing on it too much. It didn't budge for them. So the dealer would be responsible for it if it broke. Breaking that bold is a bad thing from what i hear.