Yes. In terms of the social-economic balance, just to put things in perspective, about 99.9% of Canadian waters are open to industry. There is a very unbalanced balance at the moment.
Small versus large is a long-standing debate in conservation science, and it basically depends on what you protect. If you protect something that does not move, such as coral on the seabed, the enclosure can be very small because the impact would be very localized. If you protect species that move a lot, over hundreds of kilometres, it's a completely different matter. Understanding the species you want to protect will guide you towards the size that is appropriate to protect it.
There is no general, blanket recommendation I can give saying that it has to be large or it has to be small. It depends on the species you want to protect and the context.