...after getting used to the 5 my brain started approaching string placement differently. What I find helpful from a feel standpoint is if I think a 5 string instrument (rather than 4+1) with the D string situated in the center. In other words, if I want to find the C near the nut its the third fret in the center of the fingerboard rather than the 3rd string- even though logically it is the same thing.
Did you mean to say "with the A string situated in the center"? I think I know what you're getting at, though.