anyone heard the Sophia Princess 300B Mesh tubes?

Anyone heard and a/b compared these to the excellent (IMHO) Sophia Ceramic (white w/gold pins) Base tubes?
Your comments are appreciated.
Have not heard them but have a pair we were going to build an amplifier around. We changed our mind on this (building the amp) as this tube is NOT a swap for a 300b and requires unique transformers. This tube is not supported by any manufactureres building tube amps and has only been produced for Sophia. If Sophia drops production or goes belly up you will be unable to replace the tubes.

An amplifier optimized for Princess tubes with its own unique transformers might be quite an amp with around 5 watts driven conservatively.
5 watts? Surely that's a misprint on your part.

No, the engineer that designs our amps says it will put out a bit less power than a standard 300b design (7/8 watts). That is assuming it is conservatively driven, though.

The new Princess tube is a straight swap with the standard 300b tubes. Unless you make your own gear and intend to buy a bunch of these older Priness tubes you might wind up with an orphan.