I think I’d prefer a bit of white sand. Not water soluble, non corrosive.
From the For What It’s Worth Department.
I used a "gritty" additive on one boat. It worked well enough, but it wore the paint off my chairs. Maybe I used too much. The bed liner "seems" to also offer some scuff/scratch resistance. Not saying it is better but it does a good job.
A heads up for anyone using the Goop Coat It for the bottom protection. Be prepared to work quickly. It cooks off pretty fast. A helper would be a big help. For me a squeegee and foam brush worked best. The roller not so well.