I ordered the PG278Q, simply because IPS is more of a TV than a monitor, the only scenario where you would use it as a monitor is probably if you are a professional digital artist or alike. The 34UM95 is amazing beautiful, but can't support higher than 60hz refresh rates. The TN panel is a premium high end TN, and viewing angles when considering a single monitor setup are just stupid. Get the PG278Q, has much much more to offer, 3D and G-Sync. So it is future proof.
Nothing can convert to DP. DP inputs do not accept anything other than native DP signals which DVI and HDMI are not capable of without an active adapter (signal converter box). Passive DP adapter cables only go the other way: DP graphics card to DVI or HDMI monitor.