I was able to get a DNG file into my iPhone via icloud mail which allows me to send large files.

What happens?

1) When i'm looking at the photo in Photos for iOS, i'm viewing the DNG.

2) When i use GeoTagr to geotag the DNG,  the location does show in Photos for iOS.

3) When make any adjustments in Photos' native adjustments, i get a jpg preview.

4) When i transfer the photo to Photos for OS X, the jpg preview goes away and i'm viewing the raw.

5) All the adjustments i did in Photos for iOS is transfered over and i can see though adjustments are non-destructive.

6) Final answer: the location was NOT transfered over to Photos for OS X.  Even though the adjustments were transfered via sidecar, the location was not.

It is very possible that the location is in the sidecar because i see the adjustments i made in Photos for iOS but Photos for OS X is not reading the location in the sidecar. Maybe Photos for OS X will only read location data in the EXIF? I'm not sure if Photos will read location data in the IPTC. well, if the location is in the sidecar, Photos for OS X is not reading.

For me, i feel we're almost there. Only need geotagging of raws and stacks. in my view, editing RAW's in iOS is pretty good. i'm pretty happy about that.