Very interesting thread. During my search, I came across a Steingraeber D232 with the Mozart rail and Sordino, which I enjoyed quite a bit. In the end, I went in a different direction due to concern in finding an experienced tech trained and knowledgeable in maintaining the Steingraeber with its unique features (in addition to mozart and sordino, they have unique hammerhead shapes), and having access to parts for mozart, sordino, etc., as a difficult task in the US. At the time, it appeared to me that although many uprights have a similar function as the Sordino with the mute rail, I sensed from the experience of upright owners I talked to that I would rarely use this feature, which wasn't worth the added substantial cost to me. But, these were among my favorite pianos in terms of touch and tone and I applaud the company for its willingness to innovate where others have remained traditional.