phenolic vs wood carb spacer

Wooohooo. Now we're debating. Being an old hardwood flooring guy, it's just a no brainer to make a wood spacer. Plus I already have marine grade polyureathane (think Bar Top) for the cut edges. I also am a little leary of the sealing capabilities of phenolic as evidenced by all the Thermoquads I haev owned over the years. Thanks for all the input!