Hmm.... Please define necessary. By that logic, you wouldn't have a speargun when a Hawaiian sling is all you need. It's not a necessity, not much of my freediving stuff is. It's about comfort....I wouldnt spend $200 on something that really isnt necesarry...
Jim, does the Dahlak help at all with seas lice at all? That itch can be a little annoying around the swim trunks elastic. I know sting zapper and other products and tricks work, but keeping them out of the shorts would be good.