Bah. If you want to alter it for convenience reasons, then π/2 is much nicer as it gets rid of more fractions, and a quarter turn is a pretty natural unit.

But actually I prefer keeping π as it is. The relation between the half-integral values of the Γ function and π (which shows up in many integral) is rather nice. And despite 2π appearing nicer for circles, when you generalize to n-spheres, it's clear that π is more useful with the surface area of formula 2 π^(n/2) / Γ(n/2) and volume of π^(n/2) / Γ(n/2 + 1).