Excellent idea, I'm sure with a bit of tweaking of numbers this can be refined to something really special actually. I can see you've taken care to make sure that it isn't too OP, eg the raiders have to pay 10 diamond blocks to the defenders.
The thing I love about this idea is it brings back the whole hiding items malarkey, rather than just sticking all your stuff in a huge, ugly obsidian/dirt vault. More care will be taken with valuable items, such that raiders will have a hard time making a profit, which means attacks will have to be well considered and targets carefully selected. And of course, town protection, which was in the old days intended only to stop griefers, will still perform that purpose.
Basically it's great because towns will be OP to a lesser extent. Perhaps it might get rid of dirt door coverings too? They'd be pretty pointless really if the entrance to your town is secure.
The thing I love about this idea is it brings back the whole hiding items malarkey, rather than just sticking all your stuff in a huge, ugly obsidian/dirt vault. More care will be taken with valuable items, such that raiders will have a hard time making a profit, which means attacks will have to be well considered and targets carefully selected. And of course, town protection, which was in the old days intended only to stop griefers, will still perform that purpose.
Basically it's great because towns will be OP to a lesser extent. Perhaps it might get rid of dirt door coverings too? They'd be pretty pointless really if the entrance to your town is secure.