I own the 2x TC and I haven't found that it works all that well with the 50-200 (non SWD in my case). I think maybe f7 is just too dark for the autofocus to work really well. Of course technique may also have something to do with it. I'm debating whether to try the 1.4x TC, or just hold out for the 300 f4 & TC.
I used the 50-200mm with the EC-14 extensively many years ago and it worked quite well (in bright conditions). The focus accuracy and speed is dependent on the aperture and the EC-20 can have a dramatic effect on AF with slower lenses.
Ronnie -thanks for sharing your experiences in a lot of detail. Despite having a 75-300 mk II and also being quite happy with it, I also just got a 50-200 SWD for the same reason you did, e.g. lower-light, all-weather shooting and the need for much sharper images on the long end of the lens. i have not gotten an E-M1 yet, so have had to contend with a fair bit of hunting on the E-m5, but I am still very happy with the results. Your images of the Blue Angles and the F4U are great, BTW. I do love aviation and air show photography as well, but thought the SWD might be too bulky and heavy to carry around all day . I never had a big DSLR, used Olympus 4/3 before shifting to m4/3, so i never had any real basis for comparison. i brought the SWD out for a morning of bird photography and was really tired afterwards. At any rate, I can't wait for the warm weather again so I can take photos when the air shows start up in the Northeast. Look forward to seeing more of your photos.
Ok darnit. Our airshow is Sunday, and you've convinced me I should go. If nothing else, it's always good practice for BiF, and general panning. Now, do I take the monster and tripod, or just the 40-150 and em1...?