I am a firm believer of notion of wick rotation. As Lubos nicely pointed out, the most clear indication of wick rotation comes from quantum cosmology. In fact, many new recent results in different models of quantum gravity such as loop quantum gravity$^1$ (LQG), causal dynamical triangulation$^2$ (CDT), non-commutative geometry$^3$, Horava-Lifshitz Gravity$^4$, causal sets$^5$, and eventually in superstring M-theory$^6$, strongly indicate that at the very high curvatures near or at the Planck scale (totally non-perturbative quantum gravitational system) the signature of spacetime is not Lorentzian anymore and turns into a quantum version of 4-D Euclidean space which is timeless, acausal and devoid of any dynamics or evolution, describing elegantly the so called No-Bondary Proposal of Hartle-Hawking.

Cheers

--------------------------------------
$^1$See M.Bojowald, J.Mielczarek, A.Barrau, J.Grain,  G.Calcagni

$^2$See Ambjorn, Coumbe,  Gizbert-Studnicki, and Jurkieiwcz

$^3$See Lizzi, Kurkiv, D'Andrea, and others

$^4$See Horava, Melby-Thomson, and Kevin Crosvenor, as well as the K. Crosvenor lecture at the GR21 conference 2016

$^5$See L. Glaser and S.Surya, as well as Glaser, D.O'Connor and Surya; forthcoming

$^6$See C.Hull, Edward Witten, Robbert Dijkgraaf, Ben Heidenreich, Patrick Jefferson, and Cumrun Vafa 2016