The 250P is definately something you would be happy with if you plan on doing a lot of thicker material.
I have been playing around with the IMG 200 the last couple of days and i think for my own needs this is perfect , but you also need to keep in mind i rarely go over 1/4" thick . I did however try it on 1/2" and it impressed me ( Although admitedly this is not hard to do ) I am not sure i would choose the 200 if i was planning on doing mostly 1/2" . TheIMIG 250P withthe pulse feature would be a big plus .
Cheers