Travelled United A320 Las Vegas/Washington earlier this month.
Yes they do offer ATC transmission/replies on channel 9 but don't appear to advertise this in their in flight magazine.
It was quite interesting listening to the communication and how the crew dealt with the varying levels of 'chop' during the 4 hours 25 trip, sometimes fairly severe.
Pity United have to charge additionally for checked in baggage bags as this was a domestic flight, I did wonder why both Jet Blue and Southwest advertise their no charge hold baggage policies.