Did SORBS really cause you that much pain?
Yes. We purchased colo space for some systems that didn't need high class of service (mostly development systems.) The IP space in a former lifetime was a dialup pool for analog modems. We of course changed the reverse DNS entries, and did the normal request with SORBS. Nothign really happened. I started looking into it, and finding stories of people doing the mandatory $90 donation to get express attention, and still not getting attention (so they were reversing the paypal payments and such.) After reading all this crap, I pushed our provider, they couldn't get response from sorbs, so we ended up relaying some of the traffic through our ISP and other traffic through our mail servers that are in a better data center. We had ZERO problem with Spamhaus. They were cool. Fast. Worked. The problem of course is that customers that don't know any better use mail servers that are setup for SORBS. Trying to explain it to non-tech folks is futile. The people that run SORBS are obviously bored with the project, and it should die.
I ask because the other possible solution is enough people do not find new space that people using SORBS stop using SORBS.
That's tough because the people that generally are using mail servers that use SORBS don't know better. They have to ask their providers, etc.