I tried out a dvi2svg perl script yesterday and found out pretty much what you did (except that my test EPUB didn't work well in AdobeViewer). The SVG files did look good in my browser, though.
More hopefully, I also tried out LaTeXML, a program to convert LaTeX to XML, and that XML to another format (HTML, XHTML, XML). The HTML works if converted to an EPUB, but the equations are in the form of images, which are hard to read and usually displayed too small on the reader. The XHTML contains MathML by default, so it won't work in any of the EPUB readers. The XML->XHTML process allows for a number of types of math markup in the output (Presentation MathML, Content MathML, and OpenMath). They already have preliminary support for converting LaTeX pictures to SVG, so I would guess that it would be possible to convert the math XML to SVG at that stage, as well. I noticed that someone already brought up that suggestion on the project's mailing list. So, although it doesn't work at present, that may be the best option in the future.
I tried some MathML->SVG converters (SVGMath and pMML2SVG) on the XHTML output by LaTeXML, but neither worked, unfortunately. It's not clear that they can't work (the errors were hard to interpret for me), but I have the feeling that neither converter is meant to work on MathML embedded in arbitrary documents. To me, a modified LaTeXML seems to be the best option.