Holley Swap?

Hey guys, so today I was talking with my boss (work at a custom hot rod and performance shop) and he was saying I could make more power by switching to a holley 570 cfm street avenger (I have a edelbrock 600 cfm 1406 carb). Questions are:

What do you guys think of holleys?
Do they lose their tune more than edelbrocks?
Harder to cold start?

What are the trade-offs is basically what I am looking for

Car is a 73 dart, 318, weiand stealth, msd ignition system timed 13* BTDC, headers, comp XE258 cam