We all know the SxS cards are more than capable of handling the slightly higher bite rate.
We also know JVC and Canon both use this same encoder and Canon also offers the 50Mbps codec.
It is amazing to me that Convergent Design is able to control this encoder with a simple firmware upgrade that increased their maximum bite rate on the Nano from 220Mbps to 280Mbps by the end users in just minutes.
Ian (Sony rep) says it can’t be done. Maybe Ian can elaborate to the OP what (if anything) is missing and/or why firmware can’t be used to offer this feature.
I’d say it is simple marketing, and that answer would work for me because I understand higher quality comes at a price.
MP