How well does the gtx 1080 handle Ursa 4.6k raw in Resolve?

Assuming I have the other hardware (cpu and hard drives..etc) what kind of performance does the GTX 1080 have when editing 4.6k raw footage? What level of a grade can you have, before playback drops below real time? Should I get the GTX 1080 ti instead?

All I have been able to find are the Tom Antos videos on editing systems. With a gtx 1070 he could get real time playback of URSA 4.6k raw. With an expensive HP box with a Titan X pascal, he got real time playback with 4.6k raw and a light grade.(Gain, lift, gamma and saturation adjustments). The titan is probably equal to the gtx 1080 ti in performance. Anyone have any experience with the GTX 1080 with 4.6k raw?