asus p106 looks OK but the 3 month warranty ha's me wary. And I could get a 1070 for the same price but better hash rates. asus p104 looks real good but no word on when it will be released or the price.
The 1080ti will not deliver twice the hashrate of the 1070. The main advantages with the 1080ti are it will likely retain its usefulness for a longer period of time (being a more powerful single card) and it allows for superior rig density. (With a fixed limit on the number of GPUs you can support using a given number of motherboards/CPUs/etc. you can get a better overall hashrate than 1060s/1070s. Achieving a similar overall hashrate with 1070s could require investing in additional hardware to host more cards.)