QC25 QC15 vs --- Technological progress or design upgrade?

Hello, I fly a lot professionally medium-haul (+ 6h) and so I have the QC25 and QC15 ordered the older parallel and tested two weeks under all scenarios. As already mentioned a thousand times the QC25 is valent. The handset itself, the shorter cable, the chic and more manageable storage etc. Everything like a bit more. The curious thing is that Bose of progress and not just from a design upgrade in QC25 spoke ... To make a long story short, the NC component is identical, but the QC15 plays actually a Nyonce clear the iPhone 4S, the Nokia N8 and the Cowon X5. Comparing both the listener rather mediocre Wolfson DAC of Galaxy Note2, so already gapes a considerable gap between the two. The QC15 plays louder and much clearer. For this sits the 15er again a pleasant ticking and "airy" on the head. After two weeks of back and forth, I have decided for the Plastikbomber QC15 and now several long-haul and medium or short-haul flights behind me. Even after 12 hours flight (with the way a battery), the QC15 still feels pleasantly. The NC on the plane is a pleasure that you do not want to miss. I get incredibly relaxed, where I am always previously gone with head and humming slightly whacked off the plane. If you want to choose between QC15 and QC25, which I can not give a clear recommendation for the QC15. Right now where prices tumble. I have paid the full price for the 15er. 3 of 5 stars corresponds according to Amazon "not bad" and all I can to the new handset after years of development just does not give, because I could see no technical progress for QC15. If the listener has been touted as 299 euros expensive design upgrade, so he deserved at least 4 stars. LG and relaxed travel.