I've been using the Lith- battery powered Dremel rotory tools for some time (the9.6 volt & 10.8 volt model.....woar out about 4 of them.
They are a great time saver , because of no extention cords.
I use them as a locksmith & there are many places without easy power access....so the Dremel rotary tool is very helpfull.
The one down side (which I hope has been addressed with the new Dremel tool) is that there is only one ball bearing in the unit (by the bit)....the rest of the bearings are bronze bushings.
The center bushing starts to walloout (from side pressure) & causes the units to fail.
Hope the new unit has ball bearings through out...if they have it will be a great machine........................wonderer