Shaman slow Tagar vs Torgor vs Turgur

[daxchunjae1912]

Hello I am currently lvl 49 and have been using Tagar's insect for many many levels. I have 2 questions:
1) Is the slow % difference significant enough to use Togor's or should I continue to save mana and use Tagars?
2) Does using the lower version of slow have any increase in resistance because it's against a higher lvl mob or does it not matter?

I know I should malo and then slow but for the sake of simplicity just focus on the different versions of slow, thanks in advance and if this question has been beaten to death before I apologize!