I have a EP5 with the 17mm/1.8 kit lens and the 12-50mm zoom. I find that generally I like using the zoom but find that I do use the 17mm in lower light. With the new 12-40/2.8 coming out I am wondering if it would be worthwhile for me to sell both lenses and upgrade to the 12-40mm. I know the 12-50mm would be easily be replaced, but would I miss the 17/1.8 - versus the 2.8 aperture on the 12-40? Any opinions are appreciated. Thanks.