I figured I would add some notes and restart the conversation to see if Fusion Charts has any support or product roadmap comments to add. We were looking for some flash style displays and settled on Fusion Charts, however when the part of the project we needed it for went in a Flex based direction we had problems and ended up dropping use of and not licensing FC. It is unfortunate because I think they have a nice and extensive set of visualization components with good licensing terms.
We ran into the sizing issues at first which was a real headache to trial and error adjust all kinds of sizing parameters (SWFLoader, in the FC xml, in the FC url, etc). But then a worse problem showed up where we had 5 gauges in a Flex based screen via SWFLoader and odd stuff started happening with HTTPService. We had onclick events on the SWFLoader which would allow us to load various xml via HTTPService when a user clicked on a specific gauge and when running over a fairly low latency normal internet connection as opposed to a local 100MB LAN the HTTP calls became totally unstable. It was strange and took awhile to realize it was related to SWFLoader somehow.
I suspect it probably is more of an Adobe issue with SWFLoader than an FC issue, but the fact remains that using old SWF in Flex apps is unreliable and not very well supported in my opinion. I hope FC plans to put out some native Flex components (SWC) or maybe Flash 9 SWF which I think might work better. In the meantime it looks like we are going to have to hire someone to create AS3 code for the couple of most important visualizations we need right away.