I live in Mn also and am considering the same thing. What about fan noise and quality.
why not buy a 55,000 btu. GET A REBATE for a higher efficiency from the gas co. etc...
I am not going to run mine everyday until below freezing temps everyday then set at about 50 degrees. 45 or 55 will be...
Both are Loud and have high warranty claims related to the control boards.
Buy a reznor. The fan is quiet and the heater is more efficient 83% and here we get a rebate from centerpoint energy gas company.
The reznor also has the ability to use outside air for combustion if you have a woodshop.