Well, let's plug some numbers in and see how it holds up.
A level 5 Wizard has the slots you list, 4 1st, 3 2nd, 2 3rd. With spell points, a 5th level Wizard has 27 spell points. A 1st level spell costs 2 points, a 2nd level spell costs 3 points, and a 3rd level spell costs 5 points.
This...