Changing the SQL Server service account - any additional considerations?
Your best bet before you change the service account would be to manually make sure all the permissions are correct.  This will allow you to also document what changes you make so in the future if you need to move the instance to a new server or set up another instance you will all ready have every thing you need.

This is also my preferred method of doing things since I have a slight mistrust of the built in GUI tools for SQL Server and prefer the command line or Windows folder management GUI for security modifications. (too many "Surprises" in the way SSMS does things"

Once you are ready to change the service account, the Sql Server Configuration Manager is the only way to go.  There are some other changes that the manager makes to the system besides just changing the account every thing runs under.