When buying my em10, I tried how it felt with the P12-35 and O12-40 lenses. Knowing the O12-40 was 80g heavier (2.8oz) didn't prepare me for how much heavier it felt from having more weight towards the front of the lens. I own the O40-150 R and am considering the P14-45. My O40-150 R feels more front heavy when fully extended, which is trivial at first, but not after an hour. The weight difference, 5g, of the 2 zooms is negligable. Is there a non-trivial difference in how the weight feels?