Thatch,
Part of the problem for me is that whenever I prototype something at the experimental level, economics dictate I generally do it with salvaged parts otherwise I couldn't afford to do it at all. I tear apart really expensive commercial electronics equipment obtained surplus for pennies on the dollar for parts and get really fine components inexpensively this way. Alas I have no 300B's in stock. The cheapest Chinese ones are still more expensive than I would want to pay for experimental components. I'm certain that there are other tubes around that can sound as good and without the power shortcomings of the trendy DHT's without the rediculous hi prices. I will explore those first. The 805 is certainly a good one, and I have those in stock. Whenever successful I'll also be doing a favor to anyone who purchases one of my amplifiers.
Are you aware that you can buy a dozen brand new 833A's (as in the big Wavac SE amp) for what that WE 300B is being offered for? Strue.
Rob