I'm inclined to agree with this. I'm not a big fan of services like Rage4 and Amazon's Route 53, pay-as-you-go being one of the reasons. There are "nicer" business models for selling authoritative DNS services, take a look at DNSMadeEasy/Dyn.
Spamhaus blocking whole IP CIDR blocks is an escalation procedure when a provider is not taking care of spam in that netblock. It is an incentive to tell your provider to clean up their network or find another provider if the existing one doesn't give a shit.
vpsboard is using Mandrill to send...
It is a matter of opinion, but legitimate businesses that send e-mails shouldn't be using WHOIS privacy services, at least on domains that send e-mails. That behaviour just looks suspicious to any mail administrator looking at traffic.
Full IPv6 support, by this I mean:
Native IPv6, no tunnel bullshit that some providers do. Seriously, providing HE tunnels to paying customers is not cool.
Give me a /64 (I realize this isn't possible with SolusVM...)
Let me set the PTR(s) or let me delegate the PTR zone to my own nameservers...