I setup sway couple days ago from source (with wlroots instead of wlc) and agree with the statement that sway now has the best hidpi support on Linux. I have UHD 15.6 inch laptop monitor and use FullHD 21.5 inch external monitor. Setting the scaling properly was super easy, and the performance is much better compared to my previous Xorg setup. The only thing missing for me currently is tray icons support.