Ludwig, thanks for finding this as well as big thanks for the galleries of all of the motorized bikes!
I'm not decided yet, but I am getting better educated.
Here's my thinking so far..
1. I ziptied a 25lb dumbbell to the back of the bike and rode it around. I could do it, but it was annoying. I'd like something lighter or something that can be removed in a few minutes - then it matters much less.
2. Compared to the engines on the classic bikes, many of the new kits are kinda ugly with engine hanging off the side as opposed to being a nicely integrated system.
3. The Shuttlebuddy seems to be a nice design. It's more than I'd like to spend, but 7 lbs and easiy removeavle. I have other questions/reservations...
a. They claim 3.5 hp which seems probably incorrect for that engine.
b. I'd ideally prefer a 4 stroke so I don't have to worry about mixing as well as because 2 strokes are usually much louder.
c. It'd be nice to see more reviews, but given the price point, it's not surprising that there aren't any.
Having the tank integrated and paying attention to being able to remove it quickly are nice design elements and worth paying something "more" for. Maybe they'd sell me their kit minus engine and I could put a 4 stroke on it.
I plan to talk to them.
4. Bikebug has a front mount 2 stroke for $324 which weighs 10 lbs and looks like it might come off quickly. Their website doesn't have many details or pictures so I emailed them.
5. This Staton setup looks nice (except for the 30 lbs) as the engine is more centered. The bike would still fold up with this setup and there wouldn't be an engine hanging off the side.
Still need to call dax too.
More pics, while I am here:
Bike with Dumbbell:
Bike with basket positioned so I can pedal without hitting it with my heel.
Pics of bikes folded, to get an idea of what might fit where..