You listed their good points, the other poster listed some counterpoints. The one post is no less relevant than the other in a discussion about possible DNS hosting options IMO.
Though I think the post would benefit from some citations to improve its relevance/usefulness otherwise it is little better than personal opinion/conjecture.
Unless you are specifically questioning the relevance of hosting spammers, on which case: If that is true (again, some examples would be helpful here) and you intend to host your own mail servers via their services not just the MX records pointing to other mail services, you could find yourself blocked by association at some point. False positives are a big problem in this area and can be much admin to clear up.
I use no-ip as dyndns for my home ip, so I can log in at home from outside. Recently at work my putty failed to connect, so I figured my internet line was down, it happens.
Came home, internet works fine. Everything looked just fine.
Back at work next day still can't connect. So I tried pinging, and I immediately see that the ip my home hostname resolves to is not what my ISP has. So I go to nslookup and try a DNS server I know (another local ISP), and it resolves to what I expected.
A bit of checking later I find that at work they've started using OpenDNS, and OpenDNS has blocked all of no-ip due to malware and spam.
Though I think the post would benefit from some citations to improve its relevance/usefulness otherwise it is little better than personal opinion/conjecture.
Unless you are specifically questioning the relevance of hosting spammers, on which case: If that is true (again, some examples would be helpful here) and you intend to host your own mail servers via their services not just the MX records pointing to other mail services, you could find yourself blocked by association at some point. False positives are a big problem in this area and can be much admin to clear up.