If the scenario you are trying to solve can be achieved using room properties without much effort (i.e. without a lot of additional server side logic) then I'd recommend you use that. Simply because most of the wiring up of events, sending notifications etc. is done already.
If however you find yourself doing a lot of server-side meddling with the properties and lock/unlock requests, then its best to just have your own RPC defined and implement your own logic.
Thats the general guidance. As such there are no significant performance or network differences. Both send/receive the parameters over JSON underneath.