Let's face some hard facts too. Our offense has been much, much better when Perry has been healthy (2005 for example) but he isn't likely to be healthy in 2007 and may never regain that burst and cutting ability that makes him who he is. And Rudi is solid and runs hard, but he isn't a great NFL RB. His longest run all of last season was 22 yards. Considering the number of touches he gets, that is absolutely terrible.
Also, 2 RBs is the obvious trend in the NFL. Look at the last 4 teams alive in the playoffs last season: Indy split carries between Addai and Rhodes, Chicago split carries between Jones and Benson, New Orleans split carries between Bush and McAllister, New England split carries between Dillon and Maroney. Watson is solid but I wouldn't want him getting 100 carries like all of these other guys on good teams did.