Seriously mate drive both i think you be very suprised and remember the Tdi is easily 130-140bhp with a quick £250 remap
Bhp means absolutely nothing without some Grunty Torque to go with it which the Tdi has and the 1.6 fsi doesn't
Only my oppinion mate but if for some reason I couldn't have my Gti id have the tdi version over any of the n/a petrol versions
My wifes 140tdi mk5 is a really spot on motor, goes very very well and more torque than a standard Gti oh and returns 600 miles on a tank of fuel where as mine struggles to return 350 miles,
Good luck in the search whatever you decide anyway