You do realize that when healers dps, they're supposed to go cleric stance and switch out when they are done right?
Tanks can use a str potion.... but is it really worth it? the 15 seconds of boost it gets them might help them gain threat in the case of a tank switch, but it's not really needed at all. Tanks stick to vit, healers stick to mind, dps stick to str/int. (Yeah vit would be a nice boost to have in the case of an AoE, but still not really all that necessary)
Also love HoneyBiscuit's idea for player made leves, just put a cap on how many you can take per day (because some people would just live at the boards and make all the money)