The build 285.3 (beta) is available in the Download Links post in the "Support Forums / Product Owner's Lounge / Fusion 2.5" forum.
The CF 2.5 patch updates all the installed exporters, you do not need to reinstall them. The individual installers for the exporters are not provided for this build yet.
Make backup copies of your MFA files before loading them with this version, and in case of problem you can reinstall the build 284.10 or 285.1 (no need to uninstall first, just reinstall the patch of the build you want to reinstall).
If any problem with this version, please post it in the bug box, don't post it in this thread otherwise the developers won't see it, thanks!
PS: this version will be available for Steam users very soon, unless a bad issue is discovered in the next couple of days (the reason why 285.2 was not uploaded to Steam).