Can anyone enlighten me on any differences between the older Olympus 40-150 and the newer "R" model? I ran into some references stating that they are the same optically, but possibly the newer model has faster focusing as well as quieter focusing for video use. And they also have different cosmetic appearances of course. I dont care much about how it looks, but if there are focus improvements then I would be interested in the newer model. I would be using this an on e-pm2 if that matters. Thanks!