I like a Light Modified as first barrel and modified as the second barrel myself. If I go opening weekend, I might do IC and Modified.
I agree if the birds are holding and you're reasonably quick on the draw. If the birds are flushing wide and/or you take your time getting on them, M/F might be better. I use a Winchester 101 in 20ga with fixed M/F and never have any problem killing them. High brass #6 shot so that I'm not way overgunned for the quail.