Balance Mastery has been giving linear benefits at least since 4.2, e.g. there haven't been breakpoints for mastery rating for quite some time now. Additionally I'd lose my DI + NG DoT extra tick if I changed any gems around, that's why I got a 40 haste gem in my boots.
Oh, and VPLC is actually best in slot now since it's been hotfixed a week or so ago (proc damage has been increased to roughly 260% of the tooltip value). So yes, I am using it over my NF.