Many people do just that, but it really depends on what you use it for. Synapse resource usage is dependent on the complexity of the rooms that it participates

Many people do just that, but it really depends on what you use it for. Synapse resource usage is dependent on the complexity of the rooms that it participates in, not the number of users. So if you intend to use it just to talk to a few friends, you'll have no problems at all. If you want to join rooms with 1000s of other servers participating then it will be hungrier.