This is a really helpful summary, thanks. I didn't realize people were already trying to achieve privacy using a kind of costly solution (block filters). We achieve better privacy at much lower bandwidth, and we would also allow you to query addresses other than your own.

The paper outlines a lot schemes with various tradeoffs, since it was published at an academic conference, so not all the numbers apply to this particular application. I would estimate that the response bandwidth overhead if we tried to make a 'private Electrum' would be about 2-5x over Electrum (still orders of magnitude less than the neutrino way). The request bandwidth would be negligible, I think. Probably the largest roadblock will be server cost, since the server needs to do an expensive computation; of course, if users pay for the service, then this isn't an issue.

If you're looking for a higher-level summary of the paper, there is also a conference talk I gave available online: https://www.youtube.com/watch?v=bI7lmKCAmA0.