I like the long-term effects, and I don't like to play poisoners. I think that the longer the effects, the more feared poisoners can be - this offsets the aggravation and time it takes to gather ingredients. I find the poisoner to be one of those classes that make you want to avoid them.... even if you can kill them.

It's kind of like winning a fight and getting your nose broken in the process. You won, but you're going to get laughed at the next day.