JDBC appebder is not a wM service. These are lists of log4j appenders (http://www.allapplabs.com/log4j/log4j_appenders.htm).
For instance file appender logs all the events to a file. JDBC appender is used to log events directly to a database.
If you are appending all log events to a database, it will use some of the connection pool and it will decrease the availability of a connection pool for the integration server whenever a jdbc adapter service calls the db.
where are you planning to log the events using log4j?
Do you have time critical processes (such as search functionality, validation) where you call the database constantly?