Sorry, I'll have to be the lone dissenter in the group.
A properly chosen tunnel ram, not a short dual quad intake, with carbs calibrated for 2X4 operation will make more power than a single carb. The key, as with anything related to a performance engine, is proper part selection and tuning. Runners that are too large and carbs calibrated for individual use will kill an engine's power every time, and your enthusiasm, because it will not work. 2 off the shelf 850's and a Victor Ram will not work on a mild 327, not even on a 600hp 496.
If you dig deep enough, almost every detractor of tunnel rams and 2-4's on an engine will give you enough info to determine that it was the buyer/tuner's incompetence that was at fault. No offense intended to present company.
Even though I like tunnel rams, if you do not have a very thorough understanding of how to tune your carbs and enjoy tinkering, you probably won't like a tunnel ram and 2 carbs. It's not easy to keep them synchronized while you make changes, and you need twice as many parts when you make changes.
So, for different reasons, I'll say stick to one carb just because it's easier. Not because it won't work. There are other areas that will need to be improved before you'll ever need to get the last 10 or 20hp that a tunnel ram and two carbs are capable of adding.