1ms means a TN panel which is lower quality. On a 144Hz panel a 4ms response time is plenty to show no obvious ghosting of the pixels. You really want IPS unless it's solely a budget issue which GSYNC is not.
Also NVidia is now starting to add some Freesync monitors to their supported list. One of the main differences though is potential color shifting due to no OVERDRIVE functionality (at least on none of the Freesync monitors they just announced).
2x DP?
I doubt it due to how GSYNC works with a dedicated module. Even one of the most recent, $2500 monitors only has one DP input and I don't think the HDMI input works with GSYNC.
https://ca.pcpartpicker.com/product/9tNv6h/asus-rog-swift-pg27uq-270-3840x2160-144hz-monitor-pg27uq
(I don't understand why they can't simply switch between the inputs. They obviously do that anyway for all monitors with more than one input... perhaps it's some lag/latency issue.)