I have both and it's down to a matter of choice. The eTap2hw is excellent and covers all the echoes that Hank used and there's reverb & tremolo for Duane Eddy as wel as slapback on the Roland section. This is a manually operated machine in the old fashioned way and you set the settings with your fingers.
The Zoom is different in as much as the sounds are programmed by the user and you select them with foot stomp styled push buttons, as well as having a swell pedal or wah wah on the G3x. There is also a foot stomp styled ETap from Stanley FX.
Each of them have their own merits and both are very good.
