Interesting, I knew that the terrain and PSI were the major contributing factors to pinch flats but your saying that weight does not impact this. Curious, some cyclists deliberately increase the psi in the rear tube simply because there is more weight bearing on the rear tube which may or may not decrease psi more dramatically. It appears you are supporting that weight does not contribute to pinch flats. I think I see what your saying.--------
I too have already experienced a leak in the front tube ... no nail or thorn visible, but it was losing 10psi/day. I put four oz of "green stuff" in it, and it seems to hold now ... BUT, when I installed the Green Stuff in the rear tube, the tube blew violently a few minutes after inflation to 60 psi! I can only assume the tube was faulty, as it was VERY thin in the 4" long section the blew, yet, when checking other cross section areas (messy job) the tube was thicker. I had a spare tube, and hope it holds, as its the same Kenda model tube as oem. I DO plan to buy better tubes soon.
That said, I must disagree regarding a few xtra pounds at the rear ... pinch flats are NOT caused by a few pounds of xtra weight, but rather, from too low a pressure for the terrain and weight. I'd guess they would not occur with a 225lb rider like me if pressures of over 4o psi is maintained, but I prefer higher pressures since the bike will roll easier, and perhaps I'd get better battery range as well.