You're on DIYMA, right? I thought your name looked familiar. Were you on ECA as well? I'm a long time lurker, as I can find the time to read, but have recently lost the extraneous cash to buy and build.
I still have one of the old 10" eD "prototype" subs that were really a TC Sounds sub. No name on the CF dust cap, no terminals on the sub, but it hits hard.
Back to the original topic, I don't know if he will have the tuning capability to turn down the sub at the port frequency to combat that curve, or even if he will want to. It all gets back to the individual desire. Wood is cheap, and the learning is worth it. Build more than one box!