I struggled with the same question. Even though its more expensive (~$300-500?), I decided to make a new deck for several reasons:
- My nonskid is in bad shape and I didn't want to spend time/effort in grinding it off of the old skin before I put a new nonskid down.
- I did not want to spend a ton of time trying to get a good blend on the cut line of the deck - getting the height right seems like a challenge and so does matching nonskid.
- I wanted to use the remaining edges of the old deck after I cut it out to support the new deck.
- Most of the new seam lines will be hard to see so screwups are hidden better.
- My new deck will sit ~ 1/4" higher but the new core will be thicker (.75 Corecell vs. .375 balsa/plywood mix) and provides a little more flotation.
- With a new deck I could vac bag the whole thing to make it stronger and not have to worry about a delamination or bond separation to the old skin. It is more like putting a new liner in the hull.
Good luck with the decision - I waffled back and forth a bunch before I cut the deck but cracking the old skin when I pulled it of confirmed the decision for my case.