I rarely drop below 18 psi front unless riding lots of sandy washes (which happens frequently in CA's Anza Borrego desert). However, in many cases, the trails can go from sandy wash to hardpack w/rocks then back to sand again. So I opt for more vs less psi in that case.
Muniac - you mentioned Heavy Duty (HD) tubes - what brand/thickness do you use? I've heard STI Ultra HD tubes (4mm) are quite sturdy, other HD tubes seem to be 2.5mm - 3mm. I'm about to replace a rear tire and might as well get a good tube.
Others please chime in w/your tube choice + experience.
Home Base: 33 N / 117.3 W