I've run all my mailers with aggressive PTR checks for about a year, and while some of my guests aren't getting all the e-mail that's sent to them, it's had no impact on me other than that periodically I have to tell some remote postmaster that their PTR's are missing or that they don't match the HELO hostname. Invariably they fix it.
... What do you suggest otherwise-responsible operators like me do, when after begging SBC for two years, my reverse DNS still isn't delegated correctly?
buy a 1U, put it in a colo center (should cost you about $50/month) and proxy all your outbound mail from there. stop thinking of broadband as anything other than a lastmile protocol between your house and your own piece of the internet core. or send SBC a copy of RFC 2317 every hour via a crontab. might not be very effective but it would sure get you talked about. since you're a customer they can't accuse you of spamming them...