i certainly agree that pallys are great tanks on the TPS side. However, atleast to start off in kara they need to pay a great deal more attention to their gear due to the fact that it is harder for them to gain uncrushability in their stats. That and that alone may be a deciding factor since your average pally vs your average warrior the warrior will be easily uncrushable and the pally wont.
however, i gladly enjoy sharing the tanking roll with good tankadins. They are great to work with and often i find they compliment well what i fall short of!