That is very interesting. While it may not be for every use or user, it would be cool to add this to a mod scope that already has envelope and trapezoid functions.
A similar circular type monitor idea was discussed in this topic with more technical detail.
http://amfone.net/Amforum/index.php?topic=25073.0Scope CRTs are now certainly in the class of old tubes no longer made, yet are still pretty cheap to get if you know where/how to look, especially the 5" ones, since most people want to use the 3 inchers. We should try to have a little fun with that technology while we can.