Well, everyone's "first hand experience" will be different. Wima makes excellent industrial caps. I used them in my Spectral DMC 10 rebuild as the final output coupling caps and they sounded good. But the Mundorf silver gold oils sounded much better in the DMC 10 by comparison. If there really was no difference (or the WIMA was superior) I doubt if Mundorf would continue to get the prices they charge over the Wima. As Nelson Pass states, audiophiles vote with their wallet.
I can't see ANY poly propylene cap out performing a teflon cap like the VH. This is quite commonly accepted and reinforced in reviews like the Humble Homemade Cap tests. What a manufacturer uses in his product may be the result of a number of factors, sound quality being only one. Costs, size and availability may be others. For example, Bryston uses an electrolytic cap in the output of their BDA products, much to my chagrin. Speaking with their engineers, they "reassured" me that this cap was chosen from listening tests. My own tests with that cap removed proved they were sadly mistaken. The BDA sounded much better with that cap removed. BTW, Bryston only uses this cap to remove the very small DC offset, no other reason.
I can't see ANY poly propylene cap out performing a teflon cap like the VH. This is quite commonly accepted and reinforced in reviews like the Humble Homemade Cap tests. What a manufacturer uses in his product may be the result of a number of factors, sound quality being only one. Costs, size and availability may be others. For example, Bryston uses an electrolytic cap in the output of their BDA products, much to my chagrin. Speaking with their engineers, they "reassured" me that this cap was chosen from listening tests. My own tests with that cap removed proved they were sadly mistaken. The BDA sounded much better with that cap removed. BTW, Bryston only uses this cap to remove the very small DC offset, no other reason.