I love the new backpack blower. I would like to see the string trimmer and hedge trimmer work from the same backpack assembly. Basically modular tool line that leaves the battery on your back instead of in your hand.
Ego does have a backpack battery for the European market, but it's a 1300 Wh monster battery aimed more at the professional user.
I agree that a backpack blower would be a great donor for a single battery holding/carrying device, especially since Ego already has the cable and dummy battery available... it seems we're one small design step away from having that system.
Hey Ego: your 7.5Ah battery would look attractive to a lot more people if they could wear it on their back. ;-)