This is huge part of the problem. With most characters having more points in Vitality now due to the increased mob damage (from the mob ability update), the small amount of health that the skill regens even at max (100 / 5 sec) is a drop in the ocean.
A great move would be to move it to percentage based, and then decide how long it should take a character with no points in regen, who is just standing around, doing nothing, taking no damage, with no food buffs, to regen from 1 to full. Personally I’d say a minute maybe two, tops. Let the skill (maxed) reduce that to half the base time, and food perhaps 3/4 of the base time (excepting the HoT food of course).
At this point full regen and food stacked might seem like its too fast/OP, but I’d also suggest that health regen ticks be delayed by damage the same way stamina regen is delayed by stamina use.
Still too OP? I dunno, I don’t think it would be, but hey lets try it and see, it can always be tweaked