Not sure if this is what you are asking about. We are not able to tune to DRM'ed channels, nor can we single out those channels. So you will just need to know which channels you will not be able to watch. If you try to play a DRMe'd channel in MC, you will most likely just get a black screen with no error messages.
With HDHomerun Prime, or other CableCARD tuners such as Ceton devices, all we need is a channel number (and the channel names from EPG data). Given a channel number, we either can tune to it (in case of non-DRM'ed channels that are part of your subscription) or can not tune to it (in case of DRM'ed channels or channels outside of your subscription). If you know a particular channel that you should be able to tune to, but it is not in the list of channels in MC, you should just manually add it.
I know this can be a hassle. I have subscription to a Comcast digital package, but I never fully know exactly which channels are part of the subscription. I just find out whether a channel that I care to watch is watchable by trying it.