If I can quantify the difference between the demo and the final product, I would say 10-15% for VE4 and its demo. However, for VE6, I would say 20-25% for X1, and 10-15% for X2. In other words, I concur that indeed there is a substantial difference between the X1 and the demo.
I myself now rely on the sound performance of my HD800 and Balancing Act (with WE300B replica and Mullard ECC35, PX4 and Sylvania 6SN7W metal base) as a reference while auditioning CIEM demos. The HD800 combo demonstrate a very transparent and neutral sound. For sure the HD800 and CIEMs are different species. And so far no demos or final product of CIEMs (including VE6 XC) outperform my HD800 setup in terms of transparency soundstage scale, or detail reproduction. Yet, I can say that the custom version of VE6 has come a long way and make it a serious competitor to HD 800 setup in terms of delivering musical enjoyment (although the CIEMs present the music in a slightly different way than the full size dynamic headphones).
In the near future I hope to have a chance to acquire or at least audition 1 plus 2, NT6, or SE-5way to as well spoil my ears!
Have you ever had a chance to do a comparison between ve6 to rhines stage 5 or fitear mh335?
I'll be going back to taiwan for holiday next month, what are some places that will provide the among ciem for demo? Thank you