(Well, maybe not a twist, but definitely an individualized version.)
I am setting out on the PCT in late April, and despite feeling like I'd finally sorted out my trail shoes, I'm again on the market. I know that the answer to the generic "shoe" question on a thru-hike is to go up a size or two to account for foot swelling and widening, so that's not really what I'm getting at, at least not directly.
Although I've only been doing serious backpacking for about 2 years and ~800ish miles or so, I walk 5-7 miles a day to/from work a lot of days and thus have wound up walking about ~1500 miles a year for the last two years. (I keep track, mostly because I clearly need more hobbies.) The walking I've already done seems to have been enough to push my feet from a size 11 (which I'd had since 8th grade or so) to at LEAST a size 12. The size 12 Cascadia 9s I took on my 2014 trips still fit nicely, but it's because they've stretched a bit with my feet (which have continued to widen), and I am willing to bet money that a new pair of size 12s would be uncomfortably snug. The issue is definitely an issue of width, and I'm now at a point where my feet are so wide/flat that virtually everything is ruled out.
Figuring that the best solution to my Cascadias being too small was to size up, I snagged a pair of size 13s, which felt great, right up until the point where I started wearing them outside (thus voiding the Zappos return policy), at which point I started to notice that my foot (wide, not long) really didn't line up well with the last, leading to weird pressure point pain and occasional numbness. Pain goes away when I go back to my comfy, but worn out, size 12s. I am experimenting with a couple of pairs of Altra Lone Peaks (which I'm pretty sure is the universal "wide/flat feet" shoe recommendation), which are working pretty well, and which also lead me to the actual question behind this thread.
After all of that preamble (and, really, kudos to anyone who read this far), my question is this- how big should I actually be shooting for in a thru-hike shoe, in terms of actual feel? Should I aim for "good fit but a little loose" (like well-fit shoes with the laces loosened) or "big, floppy clown shoes"? I feel like the wideness of my feet (I don't know the measurement, but they're pretty epic) is driving my shoe sizing factors more than it does for most people, so now that I have a decent lead with the Altras, I'm trying to get a sense of how the prevailing wisdom fits my situation. (Especially since my feet have already grown 1-2 sizes since I forsook my sedentary lifestyle.)
Basically, rather than just deciding to "go up a size," I'm trying to get a sense of how much extra room to give myself. The size 13 Lone Peaks fit better overall, but the size 14s feel a little better on the bottoms of my feet but are pretty big overall.
Sorry for the longwinded, roundabout way of asking. This is just one gear decision that I'm trying to get right on the first go, since the people that get it wrong seem to universally have miserable experiences with blisters, etc., and the people who get it right are very happy they did.
Thanks for reading this unnecessarily long post. As a reward, here's a cute bear picture I found on the internet:

