Well if you look at the Champ Micro Schematic on his page you'll see B+2 at 250V. Not sure what accounts for the discrepancy, he had a couple of revisions and it also matters whether you are measuring B+ voltage with or without tubes installed. We'd have to ask him. But no it won't vary case by case -- Ohm's Law cannot be argued with. More gain, more clean headroom. In the output section you will have less output power, less clean headroom compared to the higher voltages. In the reverb circuit you'll not be hitting the tank as hard and will have less reverb output signal. Just to be clear, nothing you are doing here is out of bounds, I wouldn't worry about it so long as your expectations are reasonable. That is to say, you've not cloned any of the 3 Champ designs we're referencing, it will not sound exactly like any of those amps -- your amp will have its own unique character. Since you've already selected your PT there's nothing that can be done about your B+ voltage, your B+2 to the preamp you have options though as discussed above. I'd recommend having the 3.3k and 33k dropping resistors on hand (or whichever you settle on) so you can A/B for yourself. Keep up the good work man.