It Will all depend how much you like the J30? I have had two J30s, my first was Blue J 1979, and it had core damage on the deck, but it was fast. I removed all the hardward on the cabin and deck, cut the glass where it was soft and replace with new core and the bored out the through deck fitting from beneath, then filled all the holes with resin, and then drilled new holes. I wanted to fix any problems from the past and prevent any from the future. I have solid deck that I never have to worry about, except for Katrina.
I then bought another J30 after Katrina and am in process of rebuilding her. She will be called the TOY BOX.
I love the J30, I think it is one of the best designs for a Racer/Cruiser ever thought of.
My wife and I have two year old, and one design in New Orleans maybe in the future, but PHRF and cruising, it covers all bases in my mind. Sailing in the Lake Pontchatrain and the Gulf coast, I'm sure we will many years of enjoyment.
I also hope to rebuild Blue J one day, if I can buy my partner out and have another J30 on the lake to race.
Neil