Differences in the way the fonts are rendered are, unfortunately, impossible to avoid. This is not the case for all of them, but it is for most. That's why I always try to test drive the fonts live (some foundries allow this) for different browsers and OS.
You can use SVG fonts, but you have to be aware of the browser compatibility limitations. Opera and WebKit added support for SVG, but Mozilla and Microsoft decided not to, and that limits their usefulness. Before, SVG Fonts were the only way to use webfonts on iOS devices (iPhone, iPad), and that's why FontSquirrel includes them in their font-face package, but iOS 4.2 added support for TTF fonts.
There is a proposal by the SVG glyphs for OpenType Community Group to add a subset of SVG to OpenType.
So, in short: SVG fonts render nicely, but are not supported by IE or Firefox. WOFF, TTF and others render differently depending on browser and OS, but your font will always be displayed.
About the accessibility, mentioned as a possible issue by DA01, I can't find any specifications regarding browsers either. This is the closest I got to the subject, but it talks about text in SVG graphics, not SVG fonts. It might or might not apply:
Images containing text are better served as SVG than a raster
alternative. Charts and diagrams fall under this category. In addition
to the added benefit of scalability, the text in charts and diagrams
retains the properties of text. It can be copied and pasted, searched,
and easily updated. Image headers containing decorative text may be
candidates for using SVG. WOFF fonts combined with a text stroke and
gradient or pattern fill enables customized text to remain selectable
and indexed by search engines.