Lots of questions this morning.. looks like I poked an anthill. All in all lwien gets the prize and has it summed up the best; there is a direct correlation between a Dogs 'age' and the amount of hours it has run (and at what voltage). I did used to say that I thought cycling pieces up and down was harder on them but since moving to an all welded core and doing much less woodworking with complex glue-ups that isn't a concern of mine anymore. I'm sure it's still valid on some level but now I think the primary cause of aging is hours/voltage run. Those using a VVPS who can lower the Dogs temp between uses will certainly increase their Dogs longevity as they're cutting back on that voltage aspect of the equation.