That link also explains how R2R networks can do the same thing at a stable frequency (this would make measurement easier at least).

If one wants to be anal, one can worry about glitches during some transitions, but 1) there are DACs out there that will handle that properly, and 2) otherwise I can compensate for this by just turning off the PWM before changing voltages.

A cheap embedded R-2R network from digikey is DAC0800LCN-ND (8bit, 16DIP)