I recently purchased the 40-150 Pro from a user on the forum here and the lens is great. I absolutely love it. The 1.4x TC has gotten pretty good reviews as well so I picked that up a few days back. I plan to take this combination on a two month trip through southern Africa. I've read prior threads suggesting that this combination should be sufficiently sharp that it will likely offer more detail at its maximum focal length (210mm) than the 75-300mm and 100-300mm when shot at similar or even greater focal lengths. I own the 75-300mm lens and have done a bit of shooting with both lenses to draw some comparisons. I started out using a tripod, and then using both lenses handheld. My conclusions about the lenses are the same for either method. Last point, I compared jpegs, SOOC, using an E-M10. 1. The 40-150 + TC shot wide open (F4, 210mm) is NOT as sharp as the 75-300mm (F6.3, 208mm) 2. The 40-150 + TC stopped down (F5, 210mm) is about equal (perhaps VERY slightly better when using the tripod) to the 75-300mm (F6.3, 208mm) 3. Stopping the 40-150 down further does not change the above conclusion. 4. When the TC is taken out of the equation, the 40-150 noticeably outperforms the 75-300 at similar focal lengths. There are obviously many advantages to have the 40-150 Pro that I am not addressing here. The most obvious is that it is much faster. However, if I want to have similar sharpness to the 75-300mm lens, I must stop the 40-150 + TC down to F5. This means there is only a 2/3 stop advantage. This is not meaningless, but it does take away from the potentially greater speed advantage. Most of the commentary I have read about the 40-150 + TC seems to be based on general perceptions about this combination versus other telephoto options, but I haven't read much where specific comparisons are being made with a tripod in the equation. I'm curious if anyone has made similar comparisons and what the conclusions are? I may be sending this TC back in hopes that I got a bad copy. I'd really like to gain the extra speed of F4 without getting images that are worse than my comparatively cheap 75-300mm. I'll try to get some pictures posted soon.