Bill,

You know a lot more about boat construction than I do, so I'll bow to your expertise on this. All I know is that I've seen many old cats revived using the injection method and they seemed to be solid. Maybe it's an illusion.

I have a hard time picturing how your method works exactly. It seems like you'd need a lot more skill with glass and it would really need a professional. The injection system is meant to be a "do-it-yourself" solution, so it makes sense that it wouldn't be as good.

I wonder if it would be possible, using your method, to cut the deck off, fill with the micro balloon mixture and stick the deck back down?

Also, Hobie Cat Company endorses the injection method for the old boats, they actually have instructions for it at
http://www.hobiecat.com/support/tech/delam.html