The Trancendent is Class AB vs. Class A operation of the Tenor
Just FWIW, the math does not support the idea that the Tenor was class A, not if it is also 75 watts output. IME, the tube is difficult to operate in the A2 region due to the prodigious grid currents involved. The amp is class AB1, similar to the Transcendent in this regard.
The big difference is the fact that one is pentode and the other is triode. In OTLs that makes more difference than the class of operation, since you are not dealing with zero crossing issues or commutation (switching) of output devices (OTLs tend to be immune to these difficulties).