The UF8 appears to be a really superb motorised-fader controller, most especially because of its large and clear graphical readout on each channel. It certainly has me drooling, lol. I'd buy this gorgeous piece of kit in the blink of an eye if I had a thousand to splurge right now.
If you look in the Downloads & Documents tab on SSL's web page for the UF8, you'll find the freely downloadable UF8 User Guide. According to the DAW Communication/DAW Protocols section of that manual, UF8 uses the HUI protocal for working with Pro Tools, and the MCP/MCU protocol for DAWs including Logic, Cubase, Ableton, etc. Then there are detailed tutorials in the manual for working with Pro Tools, Logic, Cubase, etc. I didn't see any mention of Sibelius (or any notation app), so perhaps contacting SSL will be the best source of info for that case.
I concur with Civilization 3: I think it's typically the case that getting external hardware controller data in and out of the master host DAW is where the big potential comms issues tend to lurk. But once UF8 is well and truly hooked up with the main DAW I wouldn't expect VEP comms to present any serious obstacles.
It certainly looks like SSL have covered all the main use cases really thoroughly and of course very professionally, as one would expect of them.