Native Thunderbolt Adapter question

Hi

Im running the HD Native Thunderbolt with my macbook pro.

I have a lot of stuff connected and I try to have my computer to run as smooth as possible, using adapters with bus powered devices etc.

Have anyone noticed any difference with an adapter instead of running it off thunderbolt bus power?

I guess there most be a beneficial reason when they added the adapter option

Also In the manual it says AC Adaptor but on the back it says 12 V DC, I guess DC 12 V 1 A is correct.

The manual also claims it is sold separately, but I can't find anything in the Avid store.

thoughts?

Thanks:-)