I made 2 boards with a similar process but 2 different cores. One is made of poplar@ 5.5mm thick and one is made of aspen@ 7 mm thick. According to the stiffness charts aspen should be slightly stiffer. To test their stiffness I placed a weight on the tip of each board that overhangs 1/2 its length.
The 5.5mm thick board deflected 40% more. To me that is a significant difference. Do you think 1.5mm of core thickness will make that much difference? I realize this is not the most ideal testing conditions since the boards are not identical cores but I found the results interesting.
