I bought a charcoal Brinkmann and with the modifications, have had no problem whatsoever.  Granted I am still afraid to do Brisket on it, as I am still novice with temp control.  I have done many chickens, turkeys, and butts/picnics.  Below is the model that I followed and it makes all the difference.
http://brinkmansmokermods.com/default.aspx