Thank you for your very full and helpful reply concerning integer boundary spurs. The HMC832 is obviously a superior device regarding control of spurs.
I am very interested in your tunable reference solution using dual HMC832. Initially my design used twin VCXO references to avoid the integer boundaries, however the suggestion to use a second HMC832 as a tunable reference looks surprisingly cost effective.
Your literature mentions software to help calculate the optimum frequency distribution between the two devices, Is this available for down load?
I would be using the first HMC832 with a 10MHz reference input. This would be either a low cost TCXO, or a low phase noise OCXO.