I encourage both of you to try Russian triple mica tubes for general use and critical evaluation. I have the GEs (sitting in a box), a so-called matched pair for $30 that wasn’t well matched, and most recently a 6 pack of the triple-micas listed below. These were relatively inexpensive, in perfect condition, and perform as well as anything I’ve tried. They are a bit deeper and warmer than the GEs.
In my experience the P20 is relatively thin, jagged, and strained with (factory) double mica tubes, but reaches the same ballpark of performance with any set of triple micas.