I actually really don't like this. I took a look at the source and the images are being loaded from the original sites.
For the content creators that pay for hosting with ad revenue you're still hitting their servers and depriving them of the way that they support themselves.
It has better fonts and whitespace than bazqux (to name one I like), and it's better for reading a lot old comics. Most feed readers seem to be designed for reading today's new postings quickly rather than binge-reading old xkcd.
Glad you liked it! Here are some of the popular ones we've done: http://blog.filr.io/we-heart-webcomics/ If we've missed any of your favorites, let us know and we'll get it done.
For the content creators that pay for hosting with ad revenue you're still hitting their servers and depriving them of the way that they support themselves.