[MayeulC]

I've been running one on my server for about 4 years. My server is a computer I got for free (some dell optiplex with an i3 in it), it eats 20W of power. It works more or less well depending on available bandwidth (on ADSL attachments were a pain).

These days it's mostly fine. The database is about 15GB (including media), there are scripts around the net to clean it up (rooms you've left, etc). Joining big, federated rooms is ram-expensive with synapse, though you now can specify a maximum complexity on your server to prevent joining those. Other small federated rooms are completely fine to join, and don't cost much more than a local room (IMO, there's little point in hosting a non-federated matrix server).

I use yunohost to simplify deployment, though it has some limitations. I did give access to a few friends, but I feel like I cannot guarantee uptime even though it has been pretty good so far. Once profiles-as-rooms land, that might change, as a user could just hop on another server if mine is down.