Boosted boards are 6.8kg. The Marbel board is even lighter at 4.5kg(!), so it's even easier to carry, and the range is greater as well (16km instead of 9.6km):
https://www.kickstarter.com/projects/1664522105/marbel-the-l...
https://www.kickstarter.com/projects/1664522105/marbel-the-l...
Yes, it is possible to do everything they claim. To get it into a reliable, shipping product is another matter.
http://howtomakeanelectricskateboard.wordpress.com/ has some intersting reading
I hope they also will be able to make the board actually useful. That's the best part of the Boosted team achievement by the way. Their board (I ride the thing 2-3 days a week) is a) actually usable b) fun. There are many un-obvious variables that come into the usability equation, especially for a piece of sports/recreational gear. In my opinion, boosted had managed to circumvent some of these by building their design around a good longboard and trying 'not to ruin' the experience of a longboard. Even that took them a while, with quite a number of redesign iterations (see. http://boostedboards.posthaven.com/ ), including building a custom controller (that apparently had removed a nasty noise problem of the early releases). It looks like Marbel team decided not to go that way, they are building the board from scratch. Should make the challenge harder in my opinion. But hopefully they will overcome it and will be able to make a 3rd generation board :) that is actually useful :)