I have probably had SE535s for 10+ years (fixed once a few years ago due to wear on the shells at the MMCX connector) and found them to be more comfortable than the SE846 due to their smaller size and form factor. I did EQ them using my Qudelix 5K for a bit last year using the Orratory1990 settings with a little less treble and mostly used them to sleep since they sit more flush than the SE846. Now they are in the office and used with a little bass boost on the TW2 where I use them to drown out background noise (I sit on a trading desk and music helps me focus).
I don't find the SE846 needs any EQ and they are a clear step up in SQ, especially when it comes to the clarity in the bass, separation and soundstage. For example, I sometimes get tricked into thinking someone is talking to me when listening to live recordings and look around to find nobody there or my wife looking at me like I'm crazy, which I never really got with the SE535s. Although I do feel they share similarities in tuning, I do recall that the SE535s started sounding a bit muffled to me after I got the SE846. As noted above, I did find EQ helped. Keep in mind though that the SE846 are very sensitive and need a good source (look for low output impedance). Works fine with the TW2.
If I were buying today and we're willing to spend $500 on a pair of Shure IEMs, I would watch for sales on the SE846 instead since I do think they are a clear step up over the SE535 and Amazon does have them on sale once in a while (but do understand everyone has different budgets). If I were not so hopeful that Shure would release a new version soon, I probably would have bought another one
Disclaimer, I am a big fan of Shure and have the SE425 (hidden in a box somewhere with my unused TWS), SE535, SE846, and Aonic 50. Have also had the SE530 and SRH 840, both of which broke after years of abuse so take what I said with a grain of salt.