An advantage of a T-tail is that the endplate effect of the horizontal allows the vertical tail to be substantially (25% or so) smaller.
Another one is that the rudder is not blanked by the horizontal at very high angle of attack, making it more effective to get out of a spin.
A T-tail does not necessarily lead to deep stall tendencies, it depends on a number of factors such as wing loading, etc.
Your second listed advantage (wing slip stream) is questionable, I wouldn't list it as such.
--M
Last edited by Machdiamond; 21st Dec 2012 at 19:01.