I am using F/7.1 most of the time. That is the sweetspot for m43 before diffraction sets it. I go to 11 if i NEED to. Even 16. However, If I do, I usually take a second shot at F/7.1 to make sure I get areas of detail cleaner for compositing. (so like shots with long exposure water, or escalators, etc... I dont care if they are diffraction hit at F16 for example...but I do want whatever is still next to them sharp)
Yup, the converter brings me back to 24mm focal length equivalent. (i wish we all just spoke in degrees! 72-degree horizonal view!)
In terms of mm shift... yes it is still shifting 12mm. However, the image circle cast is still whatever the 17 tse casts. I will not hit the same edge that a full frame camera hits with the 17mm mounted. I am going to be the sensor size difference away from that point still. (plus taking into consideration the converter) Same thing being said, for those that mount a medium format sensor to the actus can still use the 17mm...but their amount of shift will be quite cut I assume as the corner gets hit sooner due to the sensor being larger in the same image circle.
Parallax is not a HUGE issue unless you are really close. The larger issue is moving the camera a minute amount when turning the knobs! I still prefer a rear shift option. The actus seems like would be the better way to go but I have yet to test it. In reality, the small amount of perspective shift due to shift lens panorama is tiny until you get withina foot or two of you subject. I find 24mm is rarely the focal length I use to get that close when making panoramas.
I also have a panoramic tripod setup. So I usually just shift to my desired position, and then use the calibrated pano head to get my shots. Gets me best of both worlds. Most software though, lightroom is decent and PTGUI is phenomenal, covers up small parallax issues pretty well. Again, this all depends on how close, and how precise/extreme you need for your results and goal. Real world use shows its less of an issue in most scenarios.
E-M1 level...its close. Not perfect. Close enough for rough leveling. I still use the bubbles on my tripod head. I usually put the grid lines on my screen. Ide rather make sure I am level vertically. I can always rotate a crooked horizon, but I don't want to keystone correct if I don't have to.