I do a lot of filming at Trade Shows & Conferences - the odd 'arty' shoot ie music video / showreel.
This includes interviews at Midshot.
Recently I used a EX3 and Small consumer camera for a keynote speech - having to lug a EX3 around is not much fun so looking at the lighter, smaller GH4 along with a 'general' lens to replace the small consumer camera and perhaps the EX3 later down the line with a second GH4. This is intended for run and gun - with little time to change lenses.
The EX3 lens is "f = 5.8 mm to 81.2 mm (equivalent to 31.4 mm to 439 mm on 35 mm lens)"
So i was thinking off the general Panasonic 14-140mm (equivalent to 28-280mm) but this looses f stops as you zoom in - so 3.5 down to 5.6 which would mean in low light, for zoom in shots id have to set aperture before zooming in to compensate for the reduced fstop. I had this with the Sony Z1 and its a pain.