After updating to LR CC2015.6 and PS CC2015.5 I have noticed that develop settings applied in LR to TIFFS disappear after editing the TIFFS in Photoshop (e.g. I lose my crops applied in Lightroom). It's a major part of my workflow and very annoying.
"Edit Original" means - edit the TIFF file without applying Lightroom adjustments, so in Photoshop you will see the TIFF image exactly as it was in Photoshop when Photoshop edited it previously. (So your LR crops would not carry back to Photoshop)
If you have done further Lightroom development to a TIFF image, and you want those edits back in Photoshop, you need to select "Edit a Copy with Lightroom Adjustments"