AIM
Addicted to ArboristSite
+1 on this. You don't want your return coming back below 140° or the condensation will bring an early death to your owb. Just because you are running at hotter temp doesn't mean you'll burn more wood. The fire is only going to burn to bring temp back up to set point, to reheat water the 10-15° between differentials. Myself, I prefer 180° with a 165° low for a little safety net on the bottom in case it gets hit with a load right at the kick on point so the fire can get going in time.
I know my boiler doesn't go this route. Hotter water = more wood.