KBwhokbs said..
I'm thinking board has very little to do with boost height,
Timing and kite size vs wind speed surely has everything to do with how high you fly.
Your right. Height is mainly due to technique, wind speed, board speed, kitesize and type.
But...
With all other aspects being equal the correct board will help you hold more speed and power to load and pop with more ping. That will give you more height.