Linear and Switched-Mode Supply Common Shared
I was planning on connecting both Commons together and out to the PCBs


Not a good idea - high speed digital current pulses will cause small spiky volt drops end-to-end on the "common 0V" cable and this will look like the clean analogue supply has got small spikes superimposed on it relative to the 0V ground reference point on the PCB.

This may or may not upset your sensitive analogue circuits but is it a risk worth taking? Probably not.