Don't you think a little difficult to believe that products that are advertized, sold and supported on the same website, wouldn't be compatible with each other ?
I really don't know why people spread such urban legends on the internet, which is also more silly, considering that all products are available as Trial versions so, everybody could verify this beforehand, without having to rely to "fiction"...
The only thing you'll have to take care of is that, after installing a Cloud9 product that hasn't an FSDT installer yet (the updated list is on the Cloud9 section), you might need to install the stand-alone Addon Manager. This is especially true for Cloud9 airplanes, because there are updates for them that are included only in the Addon Manager installer. This will last only until we finish updating all the installers, which should take a few week.
If, instead, the Cloud9 product already has an FSDT installer, then you don't have to worry about anything, and it will just work.
