Return temps are important for those running proper temp yet sending water back to cold, if your entire water jacket is to cold, that's just as bad...
Look up the amount of dissolved oxygen content in water in regards to temp, that alone is reason enough to make folks want to run proper temps
110-120? Ok
Folks, every time I build a fire for the customer they always freak out and start hollering they have bad leak in the firebox, because the cold water surrounding the firebox makes it sweat like a pig, water will be running down the walls of the firebox and dripping out the Ash pan, once the stove gets up to around 150, this stops
I've been on numerous service calls and seen water running into ash pans, look at the control and there set at like 150, turn it up to 180, no more water .. Next time your water is cold and you build a new fire, watch the water build up on the walls of the firebox
I checked my xt the other day with an infrared thermometer, wasn't a good test but water jacket temp at top was 177, bottom was 174