Well, I can't speak for any solution when it comes to Bonjour. However, I can speak about the iMac server.
Being OS agnostic, one of the benefits I've found on OSX over Windows is its ability to create many virtual adapters. You can create an IP for each VLAN that you want to be able to AirPrint on. Here's how:
1. Open Network Preferences
2. Click the gear at the bottom of the network adapter list
3. Click Manage Virtual Interfaces
4. Click the +
5. Click New Vlan
6. Enter a name and the VLAN number (make sure Ethernet, is chosen)
7. Click Create
8. Click Done
Now you should see your new Virtual Interface in the list of adapters. You can then static an address for your iMac on that VLAN."