That's not bad. Actual network bandwidth will be higher (the way the network is connected you get the same transaction multiple times from your peers). You won't be running an always-connected-network node on your iPhone, but any low-cost server will give you twenty times that bandwidth per month. And 18GB isn't much disk space in these days of terabyte hard drives.
Not bad? huh? That seems totally broken to me.
I'm less worried about storage space than the bandwidth and time it will take a new node to enter the network.
Like you said the blocks are duplicated so a given node must download some multiple of the transactions a day. That is a tremendous amount of downloading.
Also any new node must download 216GB for each year the network has been this large!
Doesn't the system also just completely break at some point when the rate of transactions is too high? I could be wrong since I'm not sure exactly how it is decided which transactions go into a particular block. Again the pdf is kind of lacking.
Also isn't there a problem when 2 computers both solve a block before they realize the other one has? This will become more and more likely as there are more nodes.
Eventually, if Bitcoin survives and gets as popular as credit cards for paying for stuff I expect somebody will create a compatible version with a more efficient network structure (maybe by that time there will be
But it seems like a lot of these things aren't just issues of network structure. They seem inherent in the cryptographic design so it wouldn't be that straight forward to replace. Plus why not address these issues now if only to instill faith that the system is well thought out rather than just wave hands and say "computers will be faster" or "we'll tack on some better networking later"
Again I think the general idea is great and I hope the developers have good answers for all these questions. I just want to understand it/make sure it has been thought through carefully enough. I sincerely hope that it actually can work. I'd love to never have to use paypal again.