If the psychological effect of using a legendary and seeing pretty 2d lightning bubbles helps you, then go for it. Just keep in mind that those bubbles only shield a extra ~300 damage. Each proc is only giving an extra 4.5k spread out over 15 targets, while the extra SP in that same 15 second period would be an additional 6.5-7.7k. You may feel like you're doing better, but that doesn't mean you actually are doing better.