The Westone 4 sounds basically the same as a Phonak PFE with grey filters. It just needs three additional armatures, and a MSRP of $450 instead of $150. Now there are some ultra-nano-tiny differences that should be more or less irrelevant for regular listening, but they really do sound the same, all in all. There's a tiny bit more treble resolution in the W4, a tiny bit more treble sparkle in the PFE. The W4's bass rendition is a tiny bit more voluminous, yet the PFE reach down lower than the W4 and are a tiny bit faster. PFE have a tiny bit more...

Removed my silly "review", I don't want to get banned.

Review is here: http://www.head-fi.org/forum/thread/502289/panasonic-rp-hje900-zirconia-review