Thank you.
Let me try and answer some of your questions.
Durability wise I think it will hold up very well, and the great thing is it is very easy to repair, After all the foam I use is Anti fatigue mats and are meant to be walked on all day.
The glue seams will hold very well, in fact when I first decided to use this format I did some testing and once the glue between two pieces has dried if you try to pull them apart you have to rip the foam as the glued areas will not come apart.
For running around playing paintball I don't know, I do not see any reason why it will not hold up, in fact I think the benefits (Light weight, flexible, easy to repair, cheap in cost) could out way the problems. However one thing that could be a concern is the foam doesn't breath, and there for you could get very hot inside. I have never been paintballing so I do not know the type of paint you use for it, I do not know if it could be washed off the foam.
I hope this helps.
Oh and another point to show its durability is a foam Ironman helmet I made has been to schools for 2 years and has been handled by over 100 children, Dropped a lot and not one seam has split or weakened.
Also another point (sorry just thought of it), I built my son a Master Chief costume for Halloween last year, he or his younger brother have worn it at least once every week since then, running around the house running outside you name it. And I have not had to fix anything on it.
Like I said I hope this helps. And thanks again to everyone for the kind words. I will be updating my thread with some pics in a few days, I have been working on the biceps.