Funky, be really careful. Most guides I've read say not to move to ART if you're on a custom ROM. It screwed up my Gnex when I tried it (was on Shiny's 4.4 ROM). Everything FC's on you and I have to nandroid back. If you do decide to give it a shot, know that it can take a LONG time. I don't have too many apps on my Gnex and it took around 25min to convert. Good luck, just be sure to have a backup on your device if you give it a try.