This is bs. No one is insecure. I have heard WE NOS 101d, 104d, all those VT52 etc...i haven't heard your Marconi. The EML Lampi 45s and the KR valves are really good. And it is good they are improving on their previous valves.
I have compared GG to GG2 and Pacific. The biggest takeaways are get your caps and your valves right. That is what makes Lampi move from a very good dac to the best dac... Yes, it is true in different systems different valves could sound better, but it always comes down to usual suspects. Now the usual suspects level has been increased after two or three years, and that is for the better of all.
I disagree it isn't BS at all. It is true. It doesn't matter if the valves are getting better it is still true.
Listening to EML and KR all the time is just boring. Especially when you have a system to listen to all the time. Quick compares do reveal differences but a change in flavour becomes most welcome for me after over exposure to the EML KR mould.