The Triple.Fi 10 fit isn't as big of an issue as people make it out to be. Yes, you might spend a few days fiddling with them to angle them right since they are a new shape to learn. The large body also means they are largely a shallow insertion type of earphone. Some prefer a deeper, more secure fit. The shallow fit is actually good for these too given the dip in the midrange which shallow insertion helps (ear canal naturally attenuates midrange). The stock tips at times can leave something to be desired. The newer Triple.Fi 10 sets do come with Comply tips stock now which makes fitment easier for most. I would still suggest looking at buying some different types of tips to help out though. Getting the right tip makes all the difference in the world for fitment ease, comfort, and a secure fit. It's just dumb to denounce a product simply because one is unwilling to find a good tip for their ears. It does such that UE/Logitech doesn't provide more tips for what is supposed to be their flagship product. The funny thing is a good bi-flange tip makes things really easy too without needing to rely on foam, but they just don't sell the earphone with anything which is unfortunate.
Durability is on par with many other products. It's a plastic shell that's glued together just like many other earphones. You can't be stupid with the earphone, but they also don't turn to dust the instant you touch them. Yes, it would be nice to make them out of a more durable material (fiber reinforced plastics kick butt) and incorporate a screw or two. Then again, a LOT of other earphones could benefit from such things. People buy and snap off the nozzles of their new SE530 and SE535 earphones just trying to take off the stock tip, and they are some of the most over-engineered and polished earphones on the market. If I were to argue against the Triple.Fi 10, I would agree that the plastic is of a very hard and brittle type as in it will not really flex and instead crack and break before you notice you are stressing them in some way. It's just that the material is not of a soft type. The cord connection is also not built tough. It won't break on its own, but you can break it from misuse if you're manhandling the thing. I find the cord itself to be on par with most other products. I do personally like the twisted wire type of the Westone as it's flexible, has some built in stretch due to design, and carries very little microphonics. I wouldn't mind seeing more companies go that route as a standard format. There are of course aftermarket wire options for the Triple.Fi 10 if you so choose.
If these earphones are mainly for working out, I might suggest you look at Sleek Audio. Something like the Triple.Fi 10 or IE8 are a bit bulky and floppy for sport use. Sleek's SA6 and soon to come SA6R is a great choice for sport use. They are very compact and very light. As well, they offer their wireless kit to help get the cord out of the way. My bro runs with these no problem. It's one of the better portable solutions for someone who plans on being mobile.
p.s. on the RE0 comment:
No, Yuin doesn't make the Hifiman product line (RE1, RE2, RE0, RE-ZERO, RE252, RE262, HE5, HE5LE, HE6). Yuin as far as most are concerned only off earbuds in the PK1, PK2, PK3, OK1, OK2, and OK3 products and clip-on headphones in the G1, G2, and newer G1A, and G2A variants.