Have done some testing today and cannot fault the MF8380C on my local network. I don't have an MF80xx series but the machines are the same with regards to the network setup.
With regards to the Printmonitor I got you both to check, it looks like it doesn't work with this series and will give you the "Cannot monitor this printer" message after it opens. But, if you select to print a document and change the print dialog to the Finishing menu, under the image of the piece of paper will be the Printer Info button. Press this and you should see the Printer Information window, showing the device name, the communication method and what accessories are installed. Do you see this?
What I also found is that being able to print to the MF is not dependent on Bonjour working. So while the protocol does help with finding the printer on the network, you can still add the printer using IP > LPD and by entering the IP address of the MF for the Address and selecting either the Canon MF8300 Series UFRII LT or the Canon MF8300C Series in the Print Using menu.
The last thing I want you both to check is the firmware installed on the MF. This can be found by printing a System Manager Data List. On the machine, press the Report button and then select Print Reports and then System Manager Data...