Really, the biggest difference (besides not having a TA to help you out) is that there's certain things you *have* to go through your TA for. ABD will not deal directly with you if you booked through a TA. They will answer some questions, but they won't change your booking, add flights, take payments, add pre-days, etc, or anything like that without going through your TA. If you're good with that, then there's really no downside to booking through a TA, and all the upsides of having a TA to go to bat for you & sit on the phone for you & help you if there's issues.
Sayhello