Concerts can be an attracting force for new or on the edge attendees. However to do them correctly you generally need to increase your tech budget. It is important that you are sure you have sufficent volunteers and budget to do this if you are going to bring a concert.
Licencing: If an Artist is performing work that they did not write both the lyrics and the music to it is very important that you obtain a performance licence for the work. You can also build in to the contracts that it is the responsability of the artists/performers to be licenced for all work they perform.
In the US, it is the venue, not the performer, who is responsible for performance licensing; generally this is done with annual blanket license agreements with ASCAP and BMI for venues where live performances are common.