Metabones Speed Booster Adapter - Will This Attract Me to the Lumix DMC-GX7 More?

I have read about the amazing new adapters from a company called Metabones a few times, but didn't pay much attention. What's amazing about them? Not that they simply adapt various SLR lenses (including Nikkors) to Micro 4/3; I've had an adapter for that for a while now. Two things make this adapter different:

 

1. The adapter reduces the crop factor from 2x to about 1.4x on Micro 4/3, meaning that my Nikkor 20mm f2.8 SLR lens will have an equivalent crop to a 28mm lens on the GX7. That's useful.
2. The adapter makes the lens the equivalent of 1 full stop faster! So, that same 20mm f2.8 lens becomes an equivalent 28mm f2 lens on Micro 4/3.

Now, I figured this had to be some kind of gimmick. The only explanation I've seen is that it's sort of the opposite of a tele-converter (which reduces f-stop rather than increasing it). But now, I've seen it enough to look closer. For example, here's a shot from SOUNDIMAGEPLUS, using a Nikon 50mm f1.4 on the GX7 with the Metabones adapter.

Image Source: http://soundimageplus.blogspot.com/2014/03/a-superfast-alternative-panasonic-gx7.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2FpcppU+%28Soundimageplus%29

 

(Click Here) to read the post on SOUNDIMAGEPLUS and see several sample images.

 

I've read several reviews of this component, and am pretty convinced it's for real, and high quality. I may just have to give it a try.

 

(Click Here) to read more about the adapter on dpreview.com.

 

These things aren't cheap at about $430. Also, there are a few things I don't understand at this point. For some reason, the Nikon to Micro 4/3 Speed Booster adapter is listed as being for "G" series lenses. I don't know if they are fully compatible with non-G lenses (those Nikkor lenses that have an aperture ring). I also don't know if they allow for open aperture metering. I guess I'd like to test one before purchasing.

 

In any case, it's on my mind now, and I'd like to try it.

 

If anyone has answers to how these work with non-G lenses (and even non-AI manual focus lenses), please comment and let me know!

 

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