Is Radar an absolute necessity?
Radar is not an absolute necessity but can add a lot of safety and make the difference between being snug in an anchorage or waiting until daybreak to enter an unlighted harbor.
I live and sail in San Francisco and have not really felt the need for radar in the legendary fog on the bay. When I was in Mexico a few years ago radar went a long way to make up for the lack of functioning navigation aids (lights).
My use of radar is so intermitant that I dont see it as being a big threat to the amp hour budget.
As to choosing between being in the cockpit or looking at your radar display, why not do both? Put a waterproof LCD display in the cockpit.
I enjoy reading the Pardees books but have not removed my engine or thrown my batteries overboard yet. Actually I have found that the electronics on my boat rarely disappoint me and add a lot of convenience and safety to my sailing adventures.