I've done a study on 300B tubes and continue too. Here's my 2 cents. I have 2 sources I totally trust. One has compared Elrogs, PSVANE T2, old Western Electric (one of the best production runs), and Takatsuki.
Elrog performed poorly there, to the degree that he thought they were not a good match to that particular amp. Indeed, Elrog is not a WE type tube, many say these and many other tubes that are called 300Bs shouldn't be called 300B's and a different name should be given with substitution advice and warning. I don't know what happened, since TJ and Sophia are also not your regular WE but they work fine and perform fine in that amp. Expectations from Elrogs were high, the result surprising and worrying.
The other source owns old WE's, new WE's (now sold, I bought them :), Elrog, and older white base Takatsuki. He prefers the old WE's and Takatsuki.
I do not own Elrog and I haven't heard it yet. I do own Takatsuki. I did try Sophia RP, TJ Special Edition and new WE's (several of them) among other 300Bs. My strong preference is Takatsuki.
My learning from the above: 1. Elrogs might not be universally good in all SETs or it could have been a one off faulty tube or mismatch 2. Some might prefer Takatsuki.
3. I am not putting my own money on Elrogs just yet, I need much more evidence.
FY, I have 4 SETs at the moment. Coincident Frankenstein MK2, Border Patrol SE 300B, Border Patrol S20 EXD, Coincident Dynamo SE34 just to try and do some tube rolling to see their potential.
Another interesting tube is TJ Full Music CNe recently launched. I only know one source who heard it, compared to PSVANE T2 and Takatsuki and TJ SE.
