I did lowball the clock on the Titan V but only because i've not seen them consistently hit 2GHz and counting 50MHz jumps seems a bit mealy.
The OCUK timespy results are actually pretty revealing, taking the top overclock GPU score for each of the cards on OCUK
TitanV @1972/1000, GFX Score 14598 (2.85 points per cuda core)
TitanXP @2050/3106, GFX Score 11405 (2.97 points per cuda core)
1080 Ti @2151/3000, GFX Score 11267 (3.14 points per cuda core)
1080 @2190/2850, GFX Score 8552 (3.34 points per cuda core)
There's an 11% difference in clock speed between the Titan V and the GTX1080 and there's 17% difference in points per cuda core. In the scheme of things that 6% difference is pretty small compared to the overall gain in performance. Like i said there are assumptions here which i know are flawed, i'm just trying to "guess with the benefit of experience"