I've had my EVO since launch (unit #2 off the line) and just received my hopper this past Saturday.
They both work wonderfully in terms of taste and vapor production. The biggest differences, in my opinion, are the draw experience and overall usability in regards to cleaning and such.
Drawing the grasshopper through water can be a bit restricted, especially in comparison to the Evo. Using a Möbius Ion Matrix with both, I find the draw for the Evo is really easy and light on the lungs. The grasshopper is tougher, but you'll still get the vapor you're looking for if you can pull for long enough.
Cleaning the ELB's and the hopper champer is easy, though I feel like a pick is a necessity for the hopper after every spent chamber. I may be over packing the hopper, but I haven't been able to tap the hopper empty, like I can with an ELB.
Evo can take 30-45+ seconds to heat up to temperature, whereas the hopper takes 3-5 seconds. That time difference is huge to me. Ever since I got a used Herbalizer and Grasshopper, the Evo has been put away for the time being.
Hope this helps!