Hi Leslie,
We have a large amount of internal GL MOPs in the system (and we are always adding to them). It does take a while to set them up and , as I stated, you will probably be adding new ones periodically, but it makes it very easy to account for internal charges.
The MOP description is simply the GL number so that it is easy to recognize in the payment window. We originally tried to name each MOP the same as the GL account description, but found that using the raw GL worked better.
Ours are set so that only the manager user group has access to the MOPs so that the CSRs can't accidentally charge another department.
It's worked out very well for us.
Hope that helps