[frank]

Even if very high ISO settings are not pretty when offered, I wonder if their choices still mean they're less noisy than they would have been if they optimised for low ISO instead?

 

As far as I understand, a sensor has only one native ISO. All ISOs higher/lower than the native ISO are extended ISOs: they are obtained with softwares/firmwares. ISOs higher than the native ISOs are obtained by underexposing some number of stops then amplifying the brightness of the image with softwares to make the image have normal brightness; during the process noises are also amplified so extensive noise reduction is needed for high ISO images. ISOs lower than the native ISOs are obtained by overexposing a few (1-2) number of stops then de-amplifying the brightness of the image with softwares to make it have normal brightness; during this process the noise is de-amplified also so the image looks cleaner than that exposed at the native ISO.

 

Yes, even at the native ISO some amount of noise reduction is needed to make the image cleaner, but at extended higher ISOs additional noise reduction is needed, as far as I know. Extended low ISOs do not need additional noise reduction. The only problem with extended low ISOs is that in high contrast situations some highlight clipping may be caused.

 

 

 

For #2 above, would a faster shutter speed option be a desirable alternative? I've not kept up to date, but how fast do electronic shutters go these days on stills cameras?

A faster shutter speed is certainly desirable, but only a few exsiting MFT cameras offer a shutter speed up to 1/8000 sec, including the E-P5, E-PL5, GX7. Both the E-M5 and the GH3 offer a shutter speed only up to 1/4000 sec.