They idle a ton better than a Holley. The Edelbrock has a really sophisticated idle circuit with an internal restriction and air bleed setup that is designed to mix air in with the fuel. I don't have the technology to understand exactly how it works but the difference on a "hot rod" type of engine is usually very impressive.
your right, the idle/cruise circuts on the afb's are more sophisticated than the holleys. they may have as many as 4 idle/low speed air bleeds with a minimum of at least 2. the one i haven't figured out yet is the "economizer". the clusters are always mixing air with the fuel. i have a ch28 set-up that's a super driver and is more fuel efficient than any holley.
