Cam, I love these long term follow ups! For those of us who are frugal and ride a lot, this is what really matters. I'll happily spend more more on a reliable, longer-lasting product every time (except for tires, grip is king).
On those e.thirteen tires, maybe try Orange Seal if the tread is still good and you want more mileage out of them. I like both Orange and Stan's, they're good at different things. Orange Seal seems to seal anything up! But also seals up my valves too often. So I use it when needed for extra sealing, and use that valve unplugger little plastic thing every few times I inflate them. Every once in a while I need to pull the tire off to clear out the sealed up goo on the valve.
Stan's works great for normal use, not quite as crazy-good sealing, but also easier to live with. It does dry out faster than Orange over the course of a summer. It's my preferred daily driver.
I'm guessing your sidewall threads wore quickly because you like fairly low pressures, if I recall right. Now that I run slightly higher, my side knobs die first. Back in my lower pressure days, it was sidewalls with all those X-marks showing through. And rims, oh so many rims.