I like the idea of the NMs spawning in different areas. This would do a lot to remove the competition aspect since players wouldn't be actually camping a small area. In FFXI you might stumble upon an NM you knew nothing about. You would check it's strength and it would say "Bubbling Bernie's strength is impossible to gauge". This made it a lot of fun.

30 minute respawns would make NM hunting a lot less exciting and the gear drops a lot less rare. I also would only be interested in hunting for monsters who's drops are tradable. In FFXI I used to give rare items to friends on their birthdays. Sometimes I would need to spend an entire weekend hunting the same monster before I got the drop, but it made the gift that much more special.

SE probably will not have any interest in my approach to NMs. It seems the game designers are working very hard to make sure gil is of very little importance so sellable items from rare monsters would not be something they would want in their game.