I have M1 of the other 3 choices, so M2 Wild Growth is an obvious choice for me, even if an M1 book fell into my hands. On the other hand, if I didn't have the others and I got an M1 WG, I too would probably go for a respec, as the healing difference is completely negligible. I *do* nuke on raids occasionally- with *well* over 5k power, I'm always one of the last to run out unless we're being sloppy and I have to spot-heal half the raid force.