Annoyances with my gx7, em5 II or gx8 fix?

overtime I have begun to notice that my panasonic gx7 has some peculiarities that really annoy me and slow down the usage of my camera.

Number 1: constant exposure preview. For some reason in manual mode this feature is basically broken. Past a shutter speed of 1/1000 you no longer get an exposure preview. It just stops at 1/1000 and if your aperture is too bright at 1/1000 and you have a totally white image well screw you. This imo makes manual mode on the gx7 basically useless. Hopefully the gx8 doesnt share this flaw. I understand that the omd's dont behave this way.

Why would I shoot in manual mode when I cant even get an update of my exposure? Stuck using my gx7 like an outdated dslr is not an attractive idea.

this also annoys me when a flash is attached to the camera. Once a flash is attach you no longer get live exposure preview. Exposure compensation is also tied to the flash. This causes using a flash when in aperture prioity to be very unpredictable even If I am using a manual flash. This means I have to go to manual mode which is compromised in other ways to make efficient use of flash. if it still gave me a preview of my exposure with a flash attached I could use it effectively in aperture priority. I believe olympus lets you decouple flash and exposure compensation. Does it allow a constant preview with a flash attached?

Number 2: focus magnification. Maybe this is just the gx7 being stupid and other panasonics dont do this. When in manual mode and I activate magnification I can immediately take a picture from the magnified view. As soon as I hit the shutter button it starts the exposure. But in aperture priority, which I am forced to use 99% of the time due to the useless manual mode,  the magnified view has to close before it will allow you to start the exposure meaning that magnified view becomes far less effective for moving subjects who might have left the zone of perfect focus before the camera decides to take the shot. It is MUCH slower this way and I cannot figure out for the life of me why panasonic chose to do this.

Number 3: The lack of a thumb grip. The grip on the gx7 is perfectly substantial but the lack of a proper thumb rest/grip makes it very tiring to use with longer lenses and heavier lenses. This has become noticeable recently  since I got the 10.5mm nokton. After awhile my thumb begins to tire and become sore due to the way I have to grip the camera. An integrated thumb grip would make the camera many times better ergonomically.

number 4: no minimum shutter speed with auto iso. This is seriously agitating. My camera will often select a higher iso than needed when It could instead be lowering the shutter speed. Of course the function is useable but it would be more efficient if it were given a minimum shutter speed option. I understand olympus cameras have a workaround for this issue? Of course if the fixed my next point I would never need auto iso in the first place.

Number 5: iso is not assignable to one of the control dials. This is a simply an oversight. With manual lenses exposure compensation or shutter speed control always takes one dial and the other is left empty and useless. Being able to push up on the control pad and then control iso with a dial is a small consolation but it is slow and then covers the screen with an iso control overlay. It also has to be done each time I change iso meaning it is very difficult to do so fluidly.

These issues are little things that have built up and just generally give me some problems. Id like to find a camera that relieves these issue and can make my day to day shooting faster and easier. Im think the gx8 or em5 mark II. The em5 is a possibility  as is the gx9.