David, there are no different Melquides versions. Melquides is all about to use two-stage solution around cathode-ground 5E6P/6E6P with grid resistor bias where the bias voltage buffered by gas tubes. You can creates countless versions around this idea, from driving direct, low power tubes, high power tubes or even SS output stage but it will be still the same Melquides. The driver stage is the Melquides key; the 6C33 that I use at most of my channels was just my way to adopt Melquides.
I am not sure what you ask. If you ask about use full 6c33 vs. half 6c33 then… what difference it makes to you? You make the same amp and only disconnect one heater if you would like to. I do think that it would be silly to design the amp to use ONLY one heater. If you drive 6c33 then have a transformer and PS that will be able to care it with both heaters/anodes. If you chose to use juts one heater/anode then you have just a bit too overbuilt PS that never hurt and a transformer with more gap current reserve – which is also not so bad.
Regarding, your use of Melquides for your speakers or your preference to sound – I have no idea and I never sound issue such recommendation. I am not in the business of determine what would be “perfect match for you”. You might read the following advise that might help you.
Romy the caT
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche