Thanks Kevlaar. Excellent overview!
Given that your screenshot shows "Buildings:1" "Speed:100%", it seems pretty certain that the design is the same as other similar buildings which indicates a 2nd market will cut cooldown in 1/2 as Trialgame has stated.
I guess the only other question I'm hearing is are there any restrictions on what can be buffed by the Market. I know epic workyards aren't buffed by it but I've not heard of any other restrictions so am thinking all production buildings other than epics will work with it.
A question I have: does it act the same as a storehouse in regard to placement/time? In other words, does a building on either side get a 6 second travel time (24 seconds total), offset buildings top and bottom get 8 secconds (32 total) or a straight line up top and bottom 10 seconds (40 total).