I actually first started with SMIL - looking up the specs, it seemed to be widely supported in everything except Internet Explorer. I am not targeting IE for full support, and missing logo animation is absolutely a progressive enhancement. What I discovered is that the documentation on SMIL is fairly old and not comprehensive, apparently IE decided that they would never support it and the standard was supposed to be deprecated. However, after push back browser vendors have not deprecated it. In a weird twist of fate since Trident/EdgeHTML has instead been deprecated as a rendering engine, now SMIL has excellent modern browser support. I am curious as to if more folks will start using it for simple SVG animations because it is incredibly performant, if limited. In particular, I found the ease of use of chaining animations incredibly intuitive.
However, the animations that I wanted to do were just a tad too complicated for SMIL, so I had to reach for a different tool. I next took a look at CSS animations. This is where I've ended up - my logo is animated entirely with CSS. I ended up adding specific ids for each SVG element, and adding classes for the similar movements. This has led to some very tedious CSS. I imagine that if I was using a preprocessor like SASS I could consolidate this code. I decided to leave it as is because I was able to achieve most of the effect I wanted and it is incredibly lightweight from a performance perspective.
I'm pretty happy with the final animation, but it took a lot of dead ends to end up where I'm at today.