Hmm. A differing opinion here.. I have the W4R mounted to a silver dragon cable which, in my opinion, brings the W4R to another level of performance with better details, clarity, tighter bass. The stock Westone cable simply doesn't bring justice to the W4.
If both W40 and W4R doesn't differ much in SQ, I would say there's no clear winner between W40 and RE272.
Both W4R and RE272 portrays vocals really well. Smooth, lush and intimate vocals edging very marginally to the front. It's simply just right. But the RE272, IMO, wins it hands down both in details and separation. However, the W4 takes an edge back in terms of highs. W4 is much smoother and pleasing to the ears. RE272 is a tad brighter than W4. Though to me, I sense a veil over the mids with stock cable on for W4.
Soundstage wise, both are pretty similar. Maybe the RE272 edges out slightly, only marginally slightly.
Bass wise, W4 takes the lead here. RE272 is pretty soft in terms of bass although it can really keep up with very fast hitting lows. W4 focuses much more on mid bass which maybe bothersome for some but not so much to me, hence giving it a less fatiguing sound. But also at the expense of a slightly warmer sound signature.
I would say both are equally competent and good. If you prefer a slightly warmer sound signature with a smooth presentation of music for long listening hours, go for the W4R or even the latest W40. It's simply a jack of all trades though master of none. But do not pair with X3. It's just too warm for my taste.
If you prefer a brighter and analytical sound signature to slice through your music, but still with excellent vocals, stick with your RE272.
You wouldn't go wrong.