Having done the three long trails over the last four years, I’ve had some gear issues too; I think I tend to trade out my gear/clothing more often than Christine. Certainly more than some other folks I’ve hiked with; for example, the guy I finished the CDT with in November had used the same jacket on all three trails (and it showed).
So a few thoughts along this line:
Ditto Christine on the thermawrap jacket, and vest, with the caveat that it depends on which year you bought it. My thermawrap jacket originally had the sort of “hidden zipper”, which had a rubbish zipper pull (partly plastic). Montbell was very good about replacing the whole zipper when it went out, cudos to them.
I bought an OR Helium jacket for the CDT, and after wearing it a great deal on that trip (a lot more than I wore a jacket on the PCT or AT), it still seems in quite good condition, despite more sort of bushwhacking action than on the other trails. Since it’s a pretty lightweight jacket, I was impressed with that.
Pants indeed wear out, though “function over fashion”, one can wear them fairly ragged for a while when needed. As Christine said, shirts get wear marks on the back and shoulders. But you sort of look like a hobo a lot anyway, so … I’ve not really managed to wear a shirt out, though I’ve started each trail with a different one.
My underarmour boxer briefs lasted extremely well, somewhat of a surprise as I pretty much only change them for washing in town.
Golite shoes got better over time for durability, but also somewhat narrower in the toe box so I switched to Asics. I actually felt kind of bad throwing out my Asics every 500 – 600 miles last year as they looked to be in good shape each time I did so, apart from some bits of sole that were sort of almost designed to calve off (?!).
eVent gaiters and eVent mittens lasted better than expected, and w.r.t. the latter note that I’m a full-time two-stick hiker, so for those times when deployed (and again, more this last trip than others) they got a fair bit of use with trekking poles constantly in hand.
Sun gloves wear out after a while, I think I can get basically half a thru-hike out of a pair, unless I lose them (they’re sort of earth-colored after a while, can blend in if I set them down).
My OR sunrunner hat held up well into my third long trip, but I felt like my bald head was getting more tanned than it should have right through the hat so I replaced it along the way on the CDT last year.
I used Gossamer Gear Mariposa Plus packs on the PCT and about half-way into the AT. I felt like it’s true that you get about one thru-hike from one of these. In both cases it was primarily waist-belt wonkiness that triggered a shift, other stuff seemed field-repairable. My hiking partner for much of the AT had about 5000 miles on his ULA pack, so I bought a Circuit, used that for half the AT and all of the CDT and it’s still in good condition.
I think I replace my platypus bladders just as a “this seems like a good idea” thing more often than Christine. I’ve never had one leak, it’s more about (despite only putting water in them) a sense of things growing inside that leans me to replacing hose, bite valve, and/or actual bladder at times.
I used a cuben pack cover this last year, a fair bit, and had to repair one small hole with duct tape, but this held up well, I think, still in good condition. Ditto a cuben rain skirt.
Some things get so little actual wear that it’s not an issue. Tiny pocket knife, for example. Tiny reading glasses. These sorts of things one might manage to inadvertently break in a careless moment or lose, but I think never wear out.
Inflatable pads: I’ve used various, never had delamination, but have had a leak or two. My neo-air did fine on the AT, developed a slow leak shortly afterwards. Another neo-air got a slow leak along the CDT, as did my montbell inflatable pillow, but I used the latter on much of the PCT and all of the AT and CDT, so don’t feel too bad about that. It wasn’t repairable, however; it’s a shaped pillow, and the patch just wouldn’t completely seal at the specific point where the leak was.
Polycro groundcloth is pretty tough stuff; seems like I’ll go hundreds or even thousands of miles with no significant change and then something will happen so that linear tears begin and eventually they start splitting apart. But pretty cheap to replace via a local hardware store, and also something that I can certainly do without at need.
Ccf pads certainly get worn and somewhat flat over time, but remain nevertheless useable for a good long, long time. Thinner ccf pads perhaps a bit less so, but even there with care I’ve gotten more than a thru-hike out of a 1/8” ccf pad that I used most if not every night.
I too have WM bags, one summerlite and one ultralite; I’ve swapped between these to do all three trails plus other hiking. Finally now have them in to WM to restuff and in fact overfill them; even if you just lose a feather or two now and then, after more than a years worth of nights of use it does add up so that when you hold the bag up to a bright light you see why there are cold spots. Great bags, though. No zipper problems for me. One pull cord got a big wonky so that it’s a little fiddly to tighten up into true mummy mode, but otherwise holding up great.
I’m afraid I’ve swapped kitchen pieces on different trips, to include going no-cook for the first thousand miles last year. My Caldera UL compact system took some fiddling to keep going, but it does still keep going and is still my preferred cook system now when I do cook (so I’ve used it on all of the AT and more than half of the CDT). The quart sized freezer bag cooking cozy I bought from Sarbar has held up great through all three long trips.
I had been a fan of REI branded Komperdell carbon fiber trekking poles until I slipped on a patch of ice in the Smokies and snapped one. Now I’m happy with the lightest titanium leki’s I could find.
I used a TT Contrail pretty much every night on the PCT starting in the Sierras. Carried it on the AT but mostly slept in shelters. Still works great. Driven initially by wind concerns I bought a cuben upper Lightheart Solo for the CDT, and like that somewhat better. Indeed, one of the zipper pulls on that got to be unreliable, but there are two zipper pulls on that particular zipper, so I just take care now to use the other one and things are fine. No other issues, it’s a great tent.
I think that the real answer is that, for the most part, things don't often truly wear out, even “ultralight” things for the vast majority of users if some basic care is taken. Put another way, apart perhaps from packs I don’t think that durability should be stressed so much by those that question this whole “no doubt it’s just a passing fad” ultralight movement. :-)