You are Bang on my friend.I have Halcyon, EDP Ace, Avalon, Elysium as well as UM Mest mk2 and Noble Sultan.
Halcyon, Ace and elysium feels like entry level, they are very good, but not the top level, by any means.
Avalon is much more refined and can be a fair competitor for Mest mk2 for IMR house sound lovers. Avalon has less details, but for my hearing, a better “lifelike” stage feel, comparing to sterile feel on Mest.
Sultan is a league of its own, very natural and technically capable, and very fun to listen to. Definitely an endgame option for IMR lovers.
There is no doubt that Avalon and Seraph are worthy competitors to the mest mark2.
The mest has more detail and feels like I can hear more instruments in separate locations. Cymbals ,acoustic strumming sound better. Vocals not so strong though but good enough. There's a lot going on in the mest sound. Oh and the fit is crazy good. I can never get the imr iems to fit in my ears.
The Avalon has less detail but an amazing bass punch that far exceeds the mest. and all the instruments sound like one orchestra. Quite enjoyable i would say. And vocals are great on Avalon.
Both sound different and are almost in the same league. I enjoyed both yesterday.
Haven't compared the Seraph yet .
What i have realised though , is that there is more out there than IMR.
And mest mk2 is ancient , the newer iems must be killer .
The expensive stuff must be amazing.
IMR has given us great iems though.
But I need my Enigma or my money back now. Enough is enough.
Hopefully the ents go to war on the 3rd.