I was in a similar situation for the Velbus hardware I sell.
I've chosen to pay for the integration of Velbus into OpenRemote because in my opinion it offers the best flexibility for Velbus, but also the most amount of compatibility with other devices and protocols.
I'm not part of the OpenRemote management team, please remember that I'm just a user from here on
It is my understanding that there are different forks of OpenRemote, depending on your usage.
The 'demo' version, accessible via HTTP://composer.OpenRemote.org is a completely free to use, for life, design environment, where you can create the commands, sensors, switches, sliders etc that can be used in your end user interface.
This design can then be loaded into your Demo (Open Source) Controller.
This demo / free / composer version is very well supported by the community and has plenty of open source extras.
The Pro Controller has an initial sign up cost, but is supported by the management team.
This can be accessed from HTTP://designer.OpenRemote.com, once you have your Pro log in details.
The Pro account requires a different controller to be loaded into your host machines, to run the designs you create.
Above the Pro accounts there are various OEM versions, which you can apply to the management team for more information about.
As an example, the Velbus code I've paid for be available in two different forms.
The Demo version which wi be packaged with the free controller, will support up to 5 Velbus modules.
Whereas the Pro version will support an almost infinite number of modules, across multiple network segments.
I hope this information helps you decide which middleware platform to run with.