You may need a different friend for giving you advice. Copper thickness does not define the rigidity of the PCB, the thickness of the PCB does, i.e. 0.0315, 0.063 - most common, 0.091 a somewhat common stiffer upgrade. Generally though, stiffness comes from standoffs to a stiffer metal piece. 2oz refers to the copper thickness and makes little impact on stiffness.
Gold on a PCB is used where contact fingers are needed (not a factor in what you have discussed), and to passivate the copper until it is soldered. Gold (ENIG - Electroplated nickel immersion gold) is only needed if you have small pitch/complex parts. Unlikely to be any benefit for your tube amp. That gold is really thin.
Gold on a PCB is used where contact fingers are needed (not a factor in what you have discussed), and to passivate the copper until it is soldered. Gold (ENIG - Electroplated nickel immersion gold) is only needed if you have small pitch/complex parts. Unlikely to be any benefit for your tube amp. That gold is really thin.
2 Oz Coppergold double sided board for under $50 much better conductivity,as welll as longevity,and mounted on 6 standoffs