Of course, Fluid Pro is designed only for this new Muse. Also the Fluid v2.x is updated to work with the new version of Muse, but Fluid pro is completely different than Fluid v2.x and is a separate widget. Having said that, you can use both in this new version, for the Fluid V.2.x you can log-in and download the Fluid v2.x again to receive the upgraded version. Note that we have support for all the widgets you have acquired even if they are not being sold anymore, if you have any issue with Fluid v2.x please simply submit a ticket and we will be more than happy to help you solve your issue.
We would be more than happy to give you a discount on Fluid Pro, but Fluid Pro is not offered as a stand-alone product and is offered only as a part of the Ultimate Pass.