I guess it just depends on how you use your phone. I bought the G3 Tweakbox app. I used it and found the same ART, Dalvik issue. The only reason I'm running ART is basically to test it out and see if I like how it handles. Xposed should support ART once Android "L" is released.
I personally prefer the advantages of Xposed and G3 Tweaksbox. When I ran ART before we had root, my phone did appear to be smoother, but certain chromecast apps wouldn't work and I had freezing and rebooting issues.
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