The resistance is a big difference, yes you can use SS on a mech but be careful of the ohms, they can get too low for one battery mechs easily
SS will change colors, and heat up much faster than kanthal
Some people can taste a difference, some say SS tastes better, others think it tastes worse than Kanthal
SS is a little harder to build with if you don't space the coils, hot legs can happen very easily
SS needs to be dry burned much more lightly than kanthal, or it will over-oxidize and get fuzzy ash on it