Excellent point Ralph! Properly executed ultralinear topology is stunningly impressive. When executed properly, it is another reason why fixed (manually adjustable) output tube bias is essential, in order that output can be optimized for ultralinear topology.
So many short cuts are available in tube (well actually any) amplifier design that it is impossible to find a commercially available one that doesn't employ any of them. For example: does any manufacturer use an inductor filtered power supply instead of the much cheaper (and lighter) capacitance filtered power supply? None that I know of. The only way to get an absolutely uncompromised tube amplifier is to specifically requests such a build from a highly knowledgeable designer/builder, which will result in a very expensive and very heavy amplifier.
I'll refrain from exclaiming how extraordinarily special the amps I use are other than to state that they are the result of such a request.