> bragging SL's file size is less than Flash (say flash+air is like 20MB) is not an important point.
Not true at all. It is a very important point. AIR is a very large runtime and that has a huge effect on downloads. Even though broadband is fairly prevalent today, any "plugin" downloads larger than a few MBs have huge drop-off rates.
My meta point is that in SL4 you get most of what both Flash Player and AIR give you - all in a single runtime that is much smaller than the combination of Flash & AIR - and you only have to ask your visitor to install a single piece of software. Plus, Silverlight is already far more prevalent than AIR so you'll have a smaller percentage of visitors who need to install anything at all. Silverlight is in the 45-50% penetration range and AIR is between 10-25% depending on who's numbers you look at. That matters.
> Plus, consider SL isn't really as small as you say when you include the rather large patches that user's get via auto-update.
I don't know what you mean by this. Silverlight doesn't install updates any differently than Flash Player does. And I don't believe we push updates as often either.