AGI I have two Dasung paperlike pro monitors and one Onyx Boox tablet. In terms of response, Dasung is better. There is almost no lag on Dasung monitor when you change from screen to screen or refresh websites. You can even watch youtube videos on Dasung monitor, but there is no color. It will be the best if there is a HDMI 2.0 port on your laptop to use Dasung. Otherwise you will need a converter which may not give you full performance.
Boox tablet has noticeable lag when the screen is refreshed, but I have not tried to use it as a monitor. Not sure if the performance is better when used as a monitor. I like the tablet because it makes things easier for travel. Going thru airport security check is a pain when you have a laptop and a monitor with you.
I am also thinking about getting a yotaphone you mentioned in your other posts. It is pretty expensive on ebay (~$800).