Re: Permanently keeping the 1MB (anti-spam) restriction is a great idea ...

.... now would you like to quantify 'about' how much bandwidth 1 bitcoin buys you?

Here in British Columbia, and according to these numbers from 2013 ($0.45 / GB), 1 bitcoin buys you about half a TB of bandwidth.

Unfortunately not all bitcoin nodes are located in British Columbia, as lovely as it is.

Does anyone know of a comprehensive summary of bandwidth costs across the world, as well as typical upload and download bit rates?

Well that would be the real research that needs to be done wouldn't it ... so probably not, at least I haven't seen it. And you would then need to see how that translates into real bitcoin data being passed around on the real bitcoin network.