Are the check valves really necessary if the system has been converted over to the electric pump ?

Jim,

They may prevent or reduce a volume leak if there is a hole/split in the downstream hoses or loose/broken connection, & some folks add one just past the reservoir tank for that purpose - so it's one way with air pressure or pump, but usually a gravity flow leak won't pull past them.

No.

Saab tried to hit me $42 for 2 of those. IIRC, they were next to the squirter's. I ran w/o them; no isssues.

That makes the most sense, thanks for some reason, ever since I acquired the car, there was a check valve mounted behind each squirted. Worked ok for many years but when I took a closer look at the set up, it didn't make sense; plus, they had a tendency to accumulate mineral deposits resulting in a partial flow.