Since you use the Logic I believe it will have no problems, although I do not use I have installed on my machine and everything works fine, but my biggest recommendation would first check the compatibility of all software that you currently use with El Capitan before proceeding with any upgrade. I think it's too early to count on the Sierra, it will still take a while until the system is ready and be certified by the developers.
One thing you can do is a clone of your entire system using carbon on another HD and leave him as his recovery. With this exact copy of your system you do not need the boot screen, just put the cloned HD on your Mac Pro that it will start normally, I've done it!
Good luck in your upgrade!
One thing you can do is a clone of your entire system using carbon on another HD and leave him as his recovery. With this exact copy of your system you do not need the boot screen, just put the cloned HD on your Mac Pro that it will start normally, I've done it!
Good luck in your upgrade!