The advantage would be secondarys NOW! when you want them.
For a performance engine/car, yes, it is the way to go.
Theres one little tiny catch to the DP though. You'll need to be able to use the extra cfm's when you want them and that could cause a problem if the set up is not ready for them.
You'll have to tune the carb just so. To much throttle opening to early will cause a bog and the race.
Things that favor the use of a DP are;
A lighter car
Steep gears
High stall
Manual trans cars DP's.
A slightly smaller CFM needed for the cars engine is the way to go for a street car of mild performance. (This will keep velocity up when all barrels are opened to early vs a larger carb that will kill velocity and performance.)
Of hand, I don't remember your engine size and specs, but a 650 will work well on most everything small block, OE, cid.
Your foot can control most problems, but then again, the foot gets you into most problems. He he he.