Some advantages an ST11 has over an ST13:
longer swingarm arm for better high speed stability
unbolt the camshafts and they come right out (no chain or tensioner to fiddle with)
gauges easier to read in sunlight
one piece gastank with easy off cap (lock not built into cap)
change the coolant with with the fairing on and without cleaning up a mess
easier clutch slave bleed and easier to r and r
no faux valve cover to remove to add oil
better mpg (my ST11 averaged 47 mpg@85 mph indicated. The ST13 got 43)
easier airfilter change
and many more besides!