If you are are on instruments, using dual VOR with DME to navigate and receiving a Radar Advisory Service why do you imply that including a GPS in your scan as well is a good way to be spending your time?
Here is a question any one can answer (if they wish).
Your flight deck is glass - you have a screen displaying the instrument approach procedure as a nice magenta line (or if you like your non instrument course as a series of VOR turning points). The autopilot is flying the aircraft. You can either use the dual IFR certified GPS for navigation or you can use the appropriate VORs, but not both - which do you select and why?
(The point being that on many glass panels for primary nav you can do one or the other - although I accept you can monitor a different nav aid on the PDF)