From an SLF point of view:
Flights out of IAD with United on Atlantic Coast so far this year: 11
Flights out of IAD with United on Atlantic Coast 1hr late or less: 0
Flights out of IAD with United on Atlantic Coast 2hrs late or less: 7
Goodness knows what SLF actually based there have put up with.
I don't know whether ACA's performance problems were caused by the United contract or by infrastructure (ATC/IAD capacity/whatever) but I'll not be trying this outfit until I have seen the punctuality figures for at least one quarter.
Actually the Duo comparison is partly valid. If you're not an established carrier you need to get your market positioning right even to operate apparently profitable routes.