1 1/2 has always seemed kinda small to me but it is plenty strong given the wall thickness. I use 1 3/4 for pretty much everything. Its just a all around good size, not to big not to small. For something you expect to save your body, and mabye your life, go with a min of 1.20 wall, but anything thicker than 1.25 is just extra weight, in my opinion. If you really plan to thrash this thing consider heavier wall at vunerable points, like the sliders, but keep the heavy stuff down low if possible.
