I've been wearing Olu Kais leather styles for about a decade now. For me, they have always broken in and felt much more comfortable after a few days to a week of wear. You might have to try on a few pairs in the same size to find one with a comfortable thong for you. I've noticed a very slight variance from pair to pair, probably from the nature of hand crafting. Some are tighter than others.

For me, the thong part of any flipflop is the part that fails. I have never had an issue with their soles. You can get them repaired through their website and I've had a good experience with that. I've only needed to use it once though.

The arch support is unmatched in terms of flipflop brands I've tried. The leather does break in really well. I've never had an issue with their leather dye staining my feet. My leather ones usually last me about 2-3 years of (almost) daily wear from about March to October. I usually get a new pair for daily wear and the older pair becomes garage/checking the mail shoes. I could probably wear them longer but they do start looking worn by the end of year 2 and not as nice for going out.

Compared to buying multiple pairs of cheapo plastic flipflops every year, I think they're worth the price and quality. Hope this helps!