I shouldn't think apples "ovalised" ear tips make that much difference, the idea is that the tip deforms to fit the ear anyway. If you really want to go the whole hog, get some custom IEMS, that are moulded to fit your ear canal exactly with no tips:
Of course it does, it's oval AND it's not a hard stem digging into your ear. The idea that "the tips deform to fit" is actually better served Apple's way, so it's actually an argument for the form they've chosen.
As for C-IEMs. Ain't nobody got much in the way of measurements to see how those things fair. Not to mention some of the prices for ones people think are decent. But they also have issues. First being the condensation and sweat buildup is fairly fast and plentiful on all contact areas (as it would be when skin comes and maintains constant contact with plastic especially that isn't even porous). Spiral Ear has some silicone material, which just gets us back to the normal sweat condensation ordeal but perhaps slightly less discomfort (but I can't speak to that in reality since I've never tried it). But another and more serious problem, is they're all actually stupid in terms of the tri hole design (some nonsense about how they take care to make sure each driver or driver set is provided it's own optimized pathway which is pretty high on the bullshit scale because they would have to tune the entire C-IEM for every single person since the hole pathway wouldn't be completely identical). Granted I don't think this is a problem from a audible perspective (but I don't have evidence either way, just call it a hunch about it not really mattering, but it does matter since they're most likely lying about their product). Spiral Ear again gets a big mention after Crin roasted their ass over a year ago about some nonsense I'm to lazy to go dig up at the moment concerning sample variations. But the actual problem with most of the nozzles is unlike Universal IEM's, almost all C-IEM's have no dust or catch filter of any sort. A glaring flaw I'm surprised any customer puts up with. My late friend who sparked my interest in audio always talked about how useless the cleaning tool is once you have a piece of ear dust/debris fall deeper into the channel than can be dug out. Had to send the damn thing a number of times to the company for proper cleaning.
Sorry but, C-IEMs could also use work themselves. But I will give them points for comfort overall (I tried out how a proper seal could be using one of those aftermarket attachments you could have made for a U-IEM like an Andro which functions by using your ear impression).
Only real problem I have with Apple's IEM tip approach is that fucking silicon material they're using seems like some brand new research chemical garbage that is a straight poison if ingested, but for some reason has some candy smell by coincidence. It's been months of having them in use and airing out next to a open window with even sunlight baking them... And they STILL will not shed this godforsaken blueberry-ish smell. I think someone should look at what they're doing with this, as two folks I know get a rash if they have them in their ear for more than 10 minutes. You would think they'd have done their homework on this. But assuming they're doing anything more than they need to after Jobs is a stretch.
I have IEMs with custom fit but second to them, for my ear shape, are the apple ear buds, they are much more comfortable for my ear shape than any of the others (I have tried a lot over the last 40 years).
So much so, in fact, that including the extra convenience of being wireless and noise cancelling means I use them instead of the custom ones nowadays.
I was refering to their Airpods Pro's actual silicon tip design. But now that you mention Earpods (their earbuds that have been provided with devices until only as of late they decided to middle finger customers under environmental sustainability pretenses) these things are the best period. Super light, could be worn literally an entire day without noticing them, and most importantly the biggest advantage over any IEM, is your ear can actually breath easy. Their obvious only problem is they sound like anemic garbage due to their inherent design (though I did an AutoEQ, and now they sound honestly good enough to even listen to music in a quiet room believe it or not).
In the summer months like we are now, I find it hard to use anything other than earbuds. Even straight up open back headphones fail unless the AC is on full blast in three rooms.