I used a soy-based stripper for about 1/2 the hull
when I decided to take off ~30 years of buildup on our previous 34 footer. The stripper certainly softened the thick, hard layers of antifoul, and turned it into a mucky toxic slurry. It was easy to remove, but difficult to apply since it the stripper had to be covered with plastic wrap (to keep it from drying out). It was also hellishly messy. In the end I still had to do a final sanding
to get the last thin layers right off (I was going right back to the gelcoat).
On the second half of the boat I just used a large paint
scrapper to take off the outer layers. Then I finished the job, once again, with an orbital sander.
I preferred the second method. Both were physically demanding, but the cleanup was far easier keeping things dry.