AE same day changes & follow-up question..

[pilot]

Flying SFO-BOS-RDU Tuesday night...I go into the SFO AC and I check in and ask the AAngel to check on the 8am flight from BOS-RDU (I was scheduled on the 915am). She said there were plenty of seats available and since it was on AE I could pretty much just walk up and get on the flight after talking to the GA.

I must say I wasn't aware of same day changes on AE being so simple. Can someone confirm?

Also I am heading up to BOS on Sunday - returning Monday the 4th. I have two options on the BOS-RDU leg. Do I book the 645pm flight and hope I get done with my meeting early and don't get stuck in traffic and possibly miss my flight and get bumped to the 8pm flight or do I book the 8pm flight and try to show up early and get on the 645pm flight? Pros / Cons?