You don't say... perhaps it's the case of a lousy demo pair.
Now, does the UERM have the trademark BA ringing, or has it somehow avoided that issue? Less ringing than TWFK? (It's usually somewhere between 2k and 6k for BAs, typical are 3kHz or 4kHz + harmonics)
Never mind, I see it has that in Purrin's CSDs, Etymotic-like ringing pattern, not too bad but not superb. (Ye olde Knowles armature.) Pity.
More the pity since nobody sells them in the Potato Republic of Poland, so I'd have to gamble with the impressions.

RE-272s were slightly faster than RE-400, of course, but not as linear. The resolution is vastly improved by the removal of the filter/damper in the latter case - but it might be that I just happen to have a perfect fit with RE-400 and not with RE-272...