Mooring the boat isn't that expensive. In many areas you can get a mooring for about $900 or so for the season.
The primary advantage of using a mooring is simple—it is far more reliable and safer than anchoring for an extended period of time for an unattended boat. Moorings are far more reliable and far less likely to drag. Also, if a mooring breaks, the company that you rented the mooring from is usually responsible for any damage to your boat. If you were living aboard, anchoring might make more sense...but you're not.
One user on this forum had his boat anchored out and it has since sunk and been abandoned.
Placing your own mooring can be an issue, especially on the Potomac, since IIRC, the Potomac is Maryland's, and placing a mooring requires dealing with Maryland...
The primary advantage of using a mooring is simple—it is far more reliable and safer than anchoring for an extended period of time for an unattended boat. Moorings are far more reliable and far less likely to drag. Also, if a mooring breaks, the company that you rented the mooring from is usually responsible for any damage to your boat. If you were living aboard, anchoring might make more sense...but you're not.
One user on this forum had his boat anchored out and it has since sunk and been abandoned.
Placing your own mooring can be an issue, especially on the Potomac, since IIRC, the Potomac is Maryland's, and placing a mooring requires dealing with Maryland...