We have a Flex application which doesn't currently use the Flex framework as an RSL. We're considering switching, but we're not sure what proportion of users will already have the framework cached.
There's an added complication in that we're using the data visualisation components too, and we may have a choice as to which version of the framework we use. Any information is greatly appreciated -- I've tried searching, to no avail.
Adobe hasn't published any numbers on this. Sorry. But I would strongly recommend using the framework and data visualization RSLs. Version 3.3 would be a good choice. :)
I don't believe that if my app uses RSL from my site that your app will use them for your site. Once they had, they would be cached for your site but not for a 3rd party.
I think only way to have a "general" cache would be for Adobe to partner with a CDN and set up a public spot for the RSLs