Wow, never heard of that. The only thing I've seen other professionals do is double seal the seems but that's it. That siminar I am talking about I saw them have actual air chucks on these boxes with a pressure gauge. Granted it was only about 10lbs of air but after an hour, the gauge really didn't move.
Now, if your theory is correct and mine is wrong, how do you seal your paper coned sub? That's were all of your leaking is. Also, what good would it be to resin a box for airleaks like in ngsm's ported box? Like I said, you'd have to really get that resin soupy when applying it and be able to reapply it until to get it at least 1/8-1/4" for it to make it any more rigid.
You guys do know that HDF has more resin than wood don't you? Read up
http://www.teamrocs.com/technical/pages/materials.htm
http://www.keidel.com/design/select/...tl-eng.htm#HDF