[Edit] And if he isn't going oom, he wouldn't have room for more regen (because he's not technically using all he has in that case). Honestly, I don't know if he is going oom. P.S. He'd get 11 more casts (it's 4.7 casts every 6 minutes :P). But still, your numbers work out to show that the extra casts are worth more than the extra 1.5%.