New KT150 tubes?

Has anyone any experience with these pretty new tubes. There are already one or 2 amps I know of, that use them. The review of one of these amps in a UK magazine suggested they were a little warmer and more natural sounding than the nearly new KT120's

The article also suggested they were a straight swap for KT120 based amps, with no adjustment necessary. They are more than twice the cost of KT120's, but still not too costly compared with NOS tubes. I know changing from KT88's or 90's to 120's. did require some amp modification. I have an ARC reference 75 and might want to try the new tubes at some point, ARC don't seem to have a customer E-mail service, to ask the question
Spoke with DG at ARC today and he said electrically engineering has signed off A OKAY for use with the KT 150 with the
ARC amps below. But from a Mechanical standpoint one must take note with clearance and observe the larger 150s can vary on glass height with Cages and such could be a close call in some situations etc.
Enjoy, Merry Christmas
Johnny R Audio Connection
VSI 60
VSI 75
Ref 75
Ref 150
Ref 250
Ref 750
I don't own an ARC amp, but having followed this issue I feel I can finally sleep at night knowing the suspense and drama presented to the ever cautious ARC owner by the 150 dilemma is finally resolved. I gotta buy some stock in Tung Sol.
There are a quite a few ARC amps where the tubes will not clear the top cover. Be advised.
Thanks Johnny R ... finally a straight no BS answer.

Johnny, one other question. The GS-150 and Ref 150 spec identically on the ARC site. Everything .... distortion, power supply, bandwidth, whatever. So what changed??

Also, will ARC sell KT-150 tubes for regular stock Ref amps and at what price?

Johnny ... you are the best.
Note to self: Start selling larger tube cages and top covers to ARC amp owners with KT150s...maybe a lid bulge?