First off, just so everyone knows, I often play the witch in infected, and I am the one person that has probably caused all the rage to the players above me...
However, the witch was really only created for 1 purpose, which is to be able to take down players with heavy armor. I have seen players that are only semi good at pvp be able to take on crowds of 5 or more undead, at once and still live. With infected becoming more popular, its only a matter of time before a really good pvp'er gets a high level kit, and in smaller games is invincible. The witch kit is also very difficult to use, as it is really hard to throw a very slow, range limited, small splash zone potion at a player that is sprinting, so usually the only time I can even successfully throw a potion is when the human gets close to me and starts attacking me. Also, I splash myself more than other players, that I am actually trying to splash.
Even with all this said, I still think that the current duration of the poison potions at 33 seconds is too long, and should be lowered to around 15 seconds(I wouldn't lower it further otherwise the blaze is much a better kit, as it has much easier to throw firebombs, but a shorter duration).
I would also like to point out that this thread in many ways is a rage thread.