Want to do a short comparison after owning the Milaana for a few days.
Portability - Hopper hands down. The separate stem and always on battery make transporting the Milaana infinitely more difficult than throwing a pen in your pocket.
Taste - Milaana by a hair. First hit or two is just a hair better in the Milaana, I'm guessing because there's an actual air path.
Clouds - Pretty much tied. Quicker with Milaana but easier to achieve (no thinking) with Grasshopper.
Efficiency - Tied. Hopper is easier to extract fully quickly though. No thinking at all with the Hopper just grip it and rip it.
Battery life - Close but if you get a 3000mah battery with the Milaana it will probably last a bowl or two more. Both have easily swappable batteries though so not a big deal to me either way.
Looks - Hopper by a mile and a half. Milaana is kinda cool looking but the workmanship is severely lacking on my production model. Burn marks, scuffs, vice imprints, uneven sanding, scratches, etc.
Durability - I know the hopper has a lot of failures but I'm basing this just on my personal experience. Gotta give it to the Hopper. I feel like I have to be extremely careful with the Milaana because of the glass parts.
Ease of use - Grasshopper hands down. Don't have to explain how to hit it to friends just tell them to rip it like a bong and they'll get a great hit every time. Have to do a little coaching with the Milaana but everyone has gotten decent results so far with only one case of near combustion.
Let me know if you guys have any other questions comparing the two.