Thought I throw my results into the mix. My Palit Super Jetstream GTX 1070 results for overclocking:
Core +190 | Memory +520 | Power +9% --> ran stable when furmarking the hell out of it for ~2 hours.
Ended up running the card at the following specs:
Core +120 | Memory +380 | Power +2% --> cause I don't wanna stress it to the limits my card got showhn above. I concider this a resonable overclock that will last an easy 2 to 3 years for me, then I normally upgrade anyway.