Dave Local Channels 1-9 are that, local simplex channels that can be used for portable to portable comms. I have verified all 9 local channels with a MDNG radio here at work and a frequency counter (now something may have gone totally wrong with my frequency counter when I did this, so they could be wrong). The Rockville repeater, I do not know of on the MDNG System as we do not have a repeater in that area or on that frequency.
Also to all you will hear radio checks quite frequently on the MDNG System as it is tested frequently with the Force Protection Units and with other State Agencies. This is a good system to listen to as they are trying to build this system out to be a statewide reliable system.