I always use dual spectrum's when flowering and vegging actually.
Think of it this way. The sun is constantly changing and during the summer you get that nice bright light hence 6500k bulbs and as fall approaches the sun slowly moves to a mellow red spectrum the 2700k bulbs. But you gotta remember that the sun does not provide just solely 2700k when plants are flowering it also has some blues in it as well. The sun is the best dual spectrum light ever
So yes your plants will love you for a wider spectrum.
When I flower I use a 3:1 ratio for my spectrum.