I'm coming in late to this thread. We too are a hosting provider (small time), hosting approximately 1600 live domains.
Not to say tinydns is a bad alternative, as it has it's strengths, but we moved away from [outgrew] it 2 years ago.
I used to work for a messaging service provider and they had two systems. The first system was the service provider offering its messaging platform for its own domains and a hundred or so domains for quite a lot of clients and these were managed with BIND by hand.
eek. i can imagine that was a pain.
So I do not know how you 'outgrew' tinydns. After all the only part that involves tinydns is 'generate the cdb file from a database for tinydns to chew' or in other words, generating the cdb file for tinydns is the least of your problems to tackle.
Look, in no way was i bashing TinyDNS or starting a flamewar. This is why i prefaced my comment with "Not to say tinydns is a bad alternative, as it has it's strengths". By "outgrew" i mean we required more of our DNS server. We weren't a top level domain provider. Our clients required authoritative and sometimes secondary service. As a result, we required better RFC compliance and a broader range of features then TinyDNS provided. That's all. Our business simply required greater flexibility.
Generally, your business needs should determine the solution. Not the other way around.
Cheers.