In my considerable messing around with posts, augmented by some industry opinions that I trust - - - I suspect that geometry may be more important than materials. The original Thiel posts with plastic caps were compared to many 'superior' contenders and always came out on top or on top considering big price jumps for 'better'. I suspect Thiel succumbed to market pressure to have something 'better'. The later Thiel posts are gold on brass (I think), plus pretty beefy. My experiments lead me to believe that bigger is not better, and can indeed be worse due to eddy current generation due to abrupt changes in conductive mass in the presence of rapidly changing signal level and direction. I'm not a fan of beefy connectors regardless of their materials.
WBT makes a low mass, small contact x high pressure post that I am evaluating. They developed a way to deposit 3 molecule thick gold onto good copper. There are also tweaky posts which take that idea further via non-conductive carbon dshells with only a single conducting wire on the tangent. Danny Ritchie of GR research produces a thin shell tube connector. I don't know anything about Mundorf's solution.
I have no final determination, rather a developing opinion that low conductive mass is better.
I am looking forward to your Mundorf vs stock report.