Why not both?
To me it is a very different hearing experience.
I've just got Let Shuoer S12 and I like them. Had to change the Ear Tips and still experimenting with the best fit (and seal). But quality und what I hear is different.
Try different ear tips, I love Spinfit and FiiO HS20
But maybe some foamies like Comply may be a better Fit.
The zero 2 are good, but I would upgrade to the S12 or Timeless
I agree one needs both.
The sad aspect of this hobby/interest in audio reproduction tools, is obsolescence. Things are getting better. Our understanding of materials, far more people now use head worn listening devices - so there is a lot more opportunity to invest in research and development, a lot more competition - especially with the influx of lower cost products designed by Chinese original manufacturers - some of which are very very good, much bigger market, far better distribution - via online sales. So every few years, one has to check in and see what's up?
Otherwise it's so easy to live in the past, on outdated glory. I will never sell my AKG K702's, they were great for their time, but they are history, now I have heard better from IEM's, I can hear what I perceive to be distortion, in the K702's. Better is the enemy of good.
Budget, stops me from "experimenting" any further with higher value IEMs, above about $50. I have to stop somewhere. Highly interested in Planar Magnetics, was so thrilled by the ARTTI T10, for a few months, until a critical listening comparison, with Zero 2's threw up the challenges with the T10, and gave me cold feet for planar magnetics. Not saying the issues are due to the technology of planar magnetics. Just not willing at this time to shell out any serious money, unless I can 1st hear the IEM, before I buy. The S12 2024 has received universal acclaim, and I wish I could buy that, but I also abhor marketing pressure like limited editions - just an ethos I do not gravitate towards.
It has been a progression of one more impressive than the last, starting with a CCA CRA, that totally took my small device listening to another level, compared to some Sony and JVC ear buds, and the Apple EarPods. Was a revelation. Then KZ ZVX, ARTTI T10, got a KZ EDC Pro - which is better than the ZVX - but not better than the ARTTI T10, and now the 7hz Zero 2 - best I own so far, in small devices.
It's getting harder to justify why I should spend more, on anything. Hard to imagine - how much better could it sound?
Yes there are times, I do wish I did not have to stick something into the ear. One terrible development of using in ears, the ears become very sensitive to every small change in sonics, due to positioning of the nozzles - depth, rotation, angle. And any difference in hearing between left and right, is "amplified". I read somewhere that for In ears, many do not have the same frequency and level of hearing in both ears, due to slight differences in the shape and length of the ear canal, so one adaptation I have had to learn is adjusting the depth in each ear, until I can hear a MONO signal, dead center, and in some cases needing to add a bit of stereo imbalance in software on the playback device.
Headphones are more tolerant of hearing variations between the left an right ears, and speakers a whole lot more tolerant.
That's one bonus of headphone, far less need to be pedantic about stereo positioning.
But on that note, I then discover having done all this work to center the mono image on an IEM, that so many lead vocals, on music I have heard for many many years, are mixed off center - just a bit off to one side or the other. Of course some are dead center. This level of accuracy, is not something I have experienced on Over the Ear Headphones, or Speakers. So sometimes, the level of information provided in an IEM, like the Zero 2's can be a lot, so many revelations, from music one has been listening to for decades. You remember all the cues, but now, the Zero 2 pinpoints in far greater detail, the position in the stereo field, of each element in the mix.
Thinking about the HifiMan HE400SE (Stealth version) or the FiiO FT1 Pro. Not encouraged anymore to stick with good old tech like the HD6XX family of Over Ears. Happy to consider newer kids on the block.