The oak (or other hardwood) engine mount is a great idea! I will have to try that on my own bike.
The hockey puck idea does have a rational explanation. Assume all your engine mounting bolts are tight; they won't allow the engine to move against the frame tubes. What is overlooked is that the frame tubes themselves flex back and forth at the speed of the engine RPM. At a point called resonance, the vibrations from engine to frame tubes to the rider is especially bad. On my bike, that happens at around 4600 RPM according to my SenDEC tachometer.
What to do? Keep the frame tubes from vibrating. How? Make the tubes thicker (not really an option). I could wrap a heavy weight around the tubes to shift the resonant point to a much lower frequency. Hence, attaching weights such as hockey pucks to the tubes. If I could find thick strips or long rods of the metal known as lead, I would wrap the lead around the three tubes that make up the engine mounting frame.
In my case, I am able to cruise comfortably at 4200 RPM and avoid annoying vibrations until some mounting bolts vibrate loose. Then it is time to again check every bolt holding that engine to frame and tighten them all down again (until next time).
I hope this helps.
Mike
960 miles and waiting for warmer weather