Interested if anyone has advice as to whether rolling or spraying antifoul results in a longer lasting finish?
None has weighed in so I will offer what little I surmise from just knocking around over the years: notice I did not say “what little I know”.
Some of your question has to do with how smooth you want your bottom: are you racing for ex.?
And also whether you are using hard or ablative paint.
Rolling can be a pretty smooth bottom, especially if you follow up the rolling with tipping where needed. It has certainly been adequate for me over the decades and I like to sail and like to sail well. I do dive and clean the bottom when it starts to get a bit slimy. The more you do that, especially with ablative paint, the faster you will sail and the less time the bottom paint will last.
I suspect, in answer to your question, long lasting results would accrue with spraying many thin coats, letting things dry in between.
I do not know any cruisers who spray: probably because it would be a dangerous job requiring some good equipment to stay safe as well as a degree of skill (and equipment again) that rolling on paint does not demand.
Random thoughts, Dick Stevenson, s/v Alchemy