I did completely the opposite. 980 vs 970 SLI is a completely different beast to 1080 vs 1070 SLI when you compare the SLI scaling back vs x80 perf and the SLI scaling now vs x80 performance.I bought the 1070s because I felt the 1080s were a screw job just like Maxwell. The GTX 980 was quickly forgotten.
The Ti is priced the same as the x80 and equal to or faster the Titan for the second gen in a row. Those who wait are rewarded.
Essentially I avoided 1070 SLI this time because the scaling in the games I do play was shoddy, and 1080 came out better for the money for me than 1070 SLI.