Thinking about a tube roll to Brimar or Telefunken

hello I have been told by others that the 1950s Mullard long plates with
the square getters are even more open and airy on top, then the 10-m, or most Siemens or tele,with a $ 300 + price tag, for the 6922 section ,what if anything worked for you ,is the output worth doing as far as hearing a difference ? Please help me out if you can please. My Calypso preamp has only 10 hours on it from the factory, and the factory runs in in for a 100 hours.
How many hours before I hear it open up ? thanks Paul.

Well, just a note... it has been a while and I have pretty well rolled both the Aesthetix Calypso and Rhea to my extreme satisfaction. Tried many vintage tube rolls with a variety of Mullards, Amprex orange globe and Bugle Boy, Telefunken ribbed and smooth plate. In the final cut the Telefunken smooth plate and Amprex Bugle Boy Long Plate w/D getter 12ax7's were my favorite. The Bugle Boys may have an edge over the Tele's in that they sparkle just a bit while on some music the Tele's have a hint of dry presentation, but I'm splitting hairs, trust me. Both are outstanding compared to the current junk being produced today, I'll be it cheap and easy to find. The pick on 6DJ8's was the same with the Bugle Boys shining out a bit and the Tele's sounding great. These vintage tubes resolved so many things that were just plane wrong with the music from top to bottom. I notice an ease now and sweetness as well as detail along with a huge serving of soul in these vintage old valves that wasn't present in the new stuff. God have we come a long way in electronics and yet fallen desperately behind on tube design and manufacturing! One note that I find worthy of mentioning in helping the sound of my system along and making my evaluation clearer and more concise was the addition of extensive acoustic room treatments and a tube roll in my Atma-Sphere MA-1 Silver Edition power amps to Sylvania 6SN7-GTB's from the Chinese junk that they came with. These two upgrades made signal tube roll evaluation a breeze. So there you go, it's an old tale and I'm far from the first to tell it.
Happy Listening!

Thanks again to all of you who commented on this thread and help guide me along. Much appreciated as always!