I would try the $5 WinonX option first, that way you have integration like Parallels with your Mac audio apps and Cubase (like drag export from drop box) rather than having to shut down and reboot into Mac, load the files into Cubase then shutdown and back to Win to get another track.
If your Mac will take another drive it would be better rather than partitioning your Mac drive with a pseudo NTFS partition, Mac will read only Win file system and there is an HFS+ driver for Win to read your Mac file system.
You can also boot from a usb 3 drive with Windows on.

Crossgrade option looks good with the new VST/i support
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=367673

Will have to try https://jstuff.wordpress.com/jbridgem/
I don't think there is a PG integrated version for it yet as like Win,
it works in Mac OS X 10.6 to Mac OS X 10.10 only currently. Support for OS X El Capitan (10.11) is being implemented in the jBridgeM v0.94Beta.

Dual, Triple Boot your Mac
http://lifehacker.com/5531037/how-to-triple-boot-your-mac-with-windows-and-linux-no-boot-camp-required
http://twocanoes.com/products/mac/boot-runner
http://www.rodsbooks.com/refind/




www.pgmusic.com/?vid=zfM9Y6TZuoY