I have SE 5wayRef paired with dx100 and I love this combo. I used to own CA Harmony 8 pro and I did not like the pairing. With 5wayRef dx100 plays magically, with Harmony 8 pro the sound was very very good technically but it lacked this magic.
Owning Ref and having collected some opinions on Ult I also find some of the statements in jelt's review a little bit strange. I also disagree with some part of jelt's review of Harmony 8 Pro (I owned one some time ago).
IMHO everything comes down to preferences and is very subjective (even though we think that we are objective and we are assessing technical aspects of a given CIEM, in fact we are always filtering the CIEM throuhg our preferences/experience).
5wayRef and dx100 is my end game combo (mostly due to the fact that it gives me almost everything I want from SQ perspective, but I must admit that I simply lost passion for this hobby and I'm sticking with what I already achieved up to date and simply enjoy the music:))
I would say its far below 500 USD. I paid for mine approx. 450 USD. I would say on average the price for dx100 (not for hdp-r10) is 400 USD. Of course I'm referring to the fully operational units, not with, for example, broken screens.