I cant tell you about the Flander Mt. one, but I can tell you about the Coleman Golfcat heater. I bot one of these a few years ago based on a recommendation from an "old timer" at my gun club. This came with a holder that fits in a cart cup holder (which is handy when you cut a hole up in your stand to stick it in) and it also has a set of metal "feet" to hold it at an angle.
This has an electric start. It uses a AA battery and you just hold down the button....so it's not like starting a grill where you have this loud BANG to generate the spark.
The heat it gives off "shoots straight forward" and it works very well. The unit has a low and high setting.
As far as propane use, it depends on how often you are running it. If you run it on high, I'm gonna guess it will go thru a short fat tank in less than a day. But I've ran it on low for a day and not run out of gas.
I've not bot one of those refill gizmo's but that's probably a good idea.
I have a little buddy. I use it in my elevated box that is 8' x 8'. One cylinder lasts about a day when it is really cold. I never keep it running steady - still dress in warm clothes including insulated coveralls. Just use it enough to cut the cold a little. This past season one cylinder was enough. Mon, Tue, Wed, Fri pm, Sat, Fri pm, Sat.
Youth and enthusiasm will always be overcome by age and treachery.