Anyone have experience with the Tung Sol 7581a vs. EL34, KT66, KT88, 6L6


I broke down and added another power tube (Tung Sol 7581a) to my collection.  That can get expensive as my Primaluna Dialogue HP Premium integrated has 8 power tubes.   

Why has this tube escaped me thus far?  Why is it not more popular?   Many folks don't sell this reissue tube.  

I think this is a great deal.  I was torn between the lush, thick midrange of the EL34 and the more evenly spread out sound of the KT88.  But the KT88, for all its more correct behavior didn't romance me like an EL34.  

The 7581a from Tung Sol can be had cheap and I really like them.  [I'll spare you all the audiophile terms].  They check the boxes that I was looking for. 

Does anyone have experience, information or knowledge about this splendid tube?  

PS  The next experiment is KT150s but I can't see doing it if I'm gonna lose any of that great EL34 midrange. 
128x128jbhiller
@wolf_garcia ,  I'm sure folks could charge me with ignorance or blasphemy here--  I think the 7581as sound better with less than 1000 hours on them.  I think they fade off just a touch in my system after that.  
BLASPHEMY! Human perception being the key thing in all things subjective isn't always good news or any news...or accurate news anyway. I have only 2 power tubes in my single ended Had amp so it's almost too easy to look at it and wonder, "what if I put THESE back in?" Immediately I hear differences and are those differences improvements? Sometimes clearly, other times they're simply differences that take a while to get that Oh Yeah feeling...or not.
BTW,  I'll get the 7581as back in rotation again to see how they stack up to the GL KT77s.  Both are great tube compliments--I can't go wrong.
What can go wrong is Tube Reversal Compulsion Syndrome (TRCS) where an audio geek can't decide which tubes to use resulting in socket failure and, sadly, tube abuse.