I think that Glen will be able to eventually answer the question about warping...and that will be key. If the wood does not warp then using a thin piece will be processed easier & quicker.
To me, the porosity of the wood & the thickness determines the thinness of the mixture that can be used.
When you use a very weak, porous wood such as spalted woods and burls, you really need complete penetration to provide the necessary strength for thin razor scales. After you have obtained the penetration then you could go back and repeat with a thicker mix.
Regarding your 2 part poly resin........how about thinning the mix with acetone the first time to achieve penetration then repeating with a thicker mix?

Hope this helps