I think the extra 50mm (100mm equiv) at the long end tends to make me think of these two lenses as quite different. Not really comparable in the sense that if you need/want the reach, the 35-100 ain't gonna cut it

oly 40-150 / 79.4 x 160.0 mm / 880g If you need the extra reach If you need the TC option If size/weight isn't a problem panny 35-100 / 68.6 x 99.1 mm / 360g If you need OIS If you need something more compact P.S. I own the 35-100, never used the 40-150 but the images from it look really amaaaaaaazing....