If you haven't already, you may want to check out
http://epubtest.org/. They have the results of testing support for EPUB features on a variety of apps and platforms. Their tables show a number of SVG features as not supported in various apps/devices. (I am familiar with Kindles and I know that they only handle a subset of SVG and only in one of the several formats (KF8) that Amazon uses for e-books.)
I tried your new EPUB with EPUBCHECK on my Windows system and while it does take 20 minutes to complete it does not give me the I/O error you experience. I suspect a problem with your setup. There was only one error:
Code:
Validating using EPUB version 2.0.1 rules.
ERROR(RSC-007): progit-svg11-xml-img-auto.epub/titlepage.xhtml(14,69): Referenced resource could not be found in the EPUB.
(I also tried using the online
EPUB Validator, but it timed out after 10 minutes.)