It seems balanced because you have ten pros and ten cons, which might suggest that adopting Silverlight is merely a matter of taste (XAML is attractive) or politics (like for the NBC Olympics). But I think that, if you ponderate the different pros and cons, you might end-up with a balance that leans on a particular side (I let you guess which one).
The availability of designers' tools that runs on the Macintosh platform will certainly be critical if Microsoft wants to entice them out of the Macromedia world.
Similarly, the heroic efforts deployed in Moonlight to make Silverlight cross platform will be key to the overall success of this, otherwise proprietary, platform.
As of today, here is how a simple example comparing Silverlight and Flash runs on my machine:
Yep, this is a big empty white box with statistics about how fast Silverlight renders it in the status bar. If Microsoft is serious about dethroning Flash, which I am not entirely convinced of, they will have to go past this kind of... emptiness.
