Hi Chan....i tried the gp20 a couple of days ago...unfortually i tried it through a Line 6 flextone so it wasn´t the most objective test but if i were you i would go with the pod...i use a
pod pro in my rig and it must be one of the best buy i have ever done....although if you´re looking for a good
distortion pedal try a ibanez / rocktron Sharkdistortion ec20(?). It has the best distortion i have ever heard...you can dial in everything from blues to fear factory