A DRO is quieter and has very good stability and phase noise. VCO by its nature is not as quiet and should be phase locked for good stability. The VCO is less expensive than DRO. Check out the trade offs in performance. Then decide which is needed.
The "VS" series VCO has the highest frequency (10GHz nominal at this time) and smallest footprint "0.175x0.175x0.070.in" available.
Check out other mfgrs. I do not believe they build >7GHz nominal VCOs.
I hope this will be helpful.