Hi,
The Inkscape and SMIL thread is getting pretty long so I am starting a new thread on if SMIL is the right solution for animation in Inkscape.
I personally think SMIL is quite useful, but you should be aware that Microsoft has been quite forthright that they will not support SMIL in Internet Explorer. They don't want to support a second declarative animation model, the first being CSS Animations[1]. CSS Animations does have some problems, namely at the moment you can only animate style properties (things that you can set using the 'style' attribute). You cannot animate attributes (such as rectangle 'width'). This is suppose to be resolved at some point.
Having said that, the other browsers do support SMIL and SMIL is not at risk of being dropped from SVG 2 (as was SVG fonts last week). (Although, I know of at least one Chrome developer who might be happy to see SMIL go.) If there is enough demand from designers for SMIL, Microsoft has been known to change its mind (they weren't going to implement SVG filters at first). But this is someone of a chicken and egg problem. There is the "FakeSmile" JavaScript library that can be used with IE so lacking native support in IE may not be that big of a deal.[2]
There is precedence for Inkscape to lead the way. I've had one person who has been around SVG for a long time tell me that without Inkscape SVG would not now be part of HTML5.
BTW, I have a page where I created the same animation using SMIL, CSS Animations, and JavaScript.[3] Note that browser support for declarative animation, either via SMIL or CSS Animations is full of little quirks so the tests may or may not work correctly depending on which version of which browser you use.
Tav
[1] http://www.w3.org/TR/css3-animations/ [2] http://leunen.me/fakesmile/ [3] http://tavmjong.free.fr/SVG/ANIMATION/