I just built xfce4-4.5.99.1 and all dependencies from source. 

I find it is not possible to retain the default printer settings. 

I selected CUPS as the backend in xfprint-settings. 
Open xfprint and select one of two printers as default. Click on save settings and close.

If I choose to print a document from mousepad, xfprint opens again and the 'print to' is again blank. Clicking save settings does not retain the selected printer as the default. In fact it appears to have no affect at all.

Also, throughout all of this the print manager is blank. Niether of the printers is shown. 

A2ps and psutils are installed, and printing is successful if I reset the default printer every time. I just don't think this is the intended functionality.

Yesterday I compiled the latest stable version of xfce4 along with all requisite dependencies from source. The only difference there was that both printers were visible in the print manager. The issue with retaining a default printer existed there which is what prompted me to build 4.5.99.1.