Unfortunately, it might be so. Unlike earlier SC5 based emitters the mentioned XP-G3 / XP-L2 has a much bigger die size because of sideways lighted LES (light emitting surface) which has a negeative impact at luminance - even in dedomed state. More informations about this here.
From quick look at first (blurry) pictures I would estimate the die size of XP-E HEW could somewhere in the range of dedomed XP-G2 or domed XP-E2, which means 1,7 to 2,4 mm². I don't think that the dedomed XP-E HEW have the same die size of dedomed 'classic' XP-E / XP-E2.
I never sanded my emitters after shaving. I used the razor and that's it. ;) (But if possible, I consider the classic 'full' dedoming which is more considerable for maximum luminance and therefore throw.)
That would be great, thank you! :)