Since the invention of YouTube, if ether could blow a head off, we would have all seen it by now.
Any electric cold weather starting aid used in conjunction with starting fluid will cause irreversable damage to a Diesel engine. If the use of starting fluids can be detected, the warranty won't cover the damage.
Manufacturers of some brands of Diesels recommend starting fluids when the temperature drops. Cold weather, slow cranking, and compression ignition don't mix.
The engine manufacturers also advise what has been previously posted about starting aids... They are not intended to correct deficiencies.
The picture is a paragraph from the Detroit Diesel 71 series highway service manual:

- 1353527842-picsay.jpg (37.47 KiB) Viewed 185 times
Prior to the previous statement the manual reads: "Under extremely low outside temperatures, the cold oil in the bearings and between the piston and cylinder walls creates very high friction and the effort required to crank the engine is much greater than when the engine is warm. "
The general consensus which I agree with is starting fluids shouldn't be necessary for cold weather starting of a cub if all systems are in good order and the engine is in good tune.
If you need to give your cub a sniff of ether during extremely low temperatures, feel free to do so without fear of damage when used as directed.