Dui, ni shuo de dui
Well, I haven’t received yet so I can’t tell, but I have similar tiles in my living room and they are absolutely flat. At least hundred times more than my current CNC MDF table top… I’ll see once the tile gets there.
At any rate, I’ve printed pla at 45C. It will be a lot better than nothing. It will all just depend on the quality of your first layer thickness.
I don’t think there is a logical limit, I think it is just a performance limit. So it will also probably depend of the outside temperature.