Live is most valuable to me because it is very cpu-friendly considering the amount of tasks being done at once in such a rich visual environment. Pd on the other hand is very slow...the equivalent of maybe 2 or 3 live devices will shoot my cpu up to 75% easily.
Of course, this is because Live devices are optimized in C++. Also, the GUI is rendered by graphing bitmap primitives onto the screen...I'm pretty sure that Pd does something different/more cpu intensive using tcl/tk.
I'm all for the effort though! I just think that Pd will need some major face lifts to get it to the usability that Live offers.