I don't think I could tell the difference in a blind test, they're that similar. Both are punchy with very accurate treble. They're also both fairly intimate, not super spacious. The Ember owns in terms of versatility though.
Well, I haven't tried them on the T50RP yet but they don't cause any sort of bass roll-off on the HE-4 (objectively). Subjectively the bass is better than the stock HFM velours, probably due to closer driver distance (they are really squishy).