ORBX is under the VOZ 1.5 on the VOZ website![]()
So it is

While I'm thinking about it, VOZ includes VOZ Flights which you'll find under Select a Flight in FS9. Also look for Koorbie Clouds under Weather.
I googled Xtra Water and found this: http://www.fsfield.com/viewfile/1391.html :
If you have voz, the textures may not show up correctly. Xtra Water was made using default textures from fs9. If you have VOZ they may not look the same because voz changes textures xtra water does not have. It may look better or worse. We haven't tested it.
It does look nice though! What you might do is back up your water textures before trying it out.
Edit: I try downloading the ORBX file. Got a Winzip error that it can't open the file: It does not appear to be a valid archive.