They are a safer chemistry battery so in that respect yes they are safer. They don't have a protection circuit so in that respect they aren't. It really depends on the application which is best to use.
In a mod that uses a booster circuit more current is needed so IMR is recommend also in the smaller sizes like 14500 with a dual battery config sometimes IMR can be the way to go for the current draw.
18650s are big enough they will have enough current draw in a dual config either way so I really don't see the point in going IMR in that situation as you'll reduce your run time in between charges but yes they both will work. In the event the
batteries go into thermal runaway IMR would be safer at that point but protected gives you a circuit that should shut the batter down before it happens.