HOME button is GUIDE button, then OK
i always consider that the device will be dualOS, then on my designs have basic android buttons, but i figure these controls may be on the keyboard too:
win = home
esc = back (well, esc have the same functionality)
context menu = menu
and yes, i prefer this layout with sticks on the border.
L3 and R3 may be on the same row as the rest of the buttons, or where you placed (but in any case, near to sticks)
select & start are well located. must be select on the left and start on the right, and easy to access
and you forget the 3-mode switch (DInput, XInput, Mouse), that i figure is the "mouse" button you put on the image.