Worth,
I have hunted out of one for over 25 years. Never flipped one, even in some strong river currents. Myself and another friend have the Maxi Poke, the slimmer model (forget what it's called) is a bit more unstable, but still never known one to be flipped.
The Maxi Poke boats are a great boat in both marshes (shallow draft) and rivers (they track very well). If you are on the fence about purchasing one, I would highly recommend making the purchase. The only drawback to the boats are they are very low profile and are maybe a little tougher to get in and out of for big guys like myself.
I don't think you will regret getting one.
Brad