Good Ol' Times....
The first ArchiCAD-> WinEst interface was part of the Builders' Edition version in 5.0 and 6.0. For the US 7.0 version all the content work of the Builders' edition was merged into the standard 7.0/residential default.
The scheme worked by defining property objects set up according to WinEst residential database ASSEMBLIES which then could be assigned to Wall/Slab composites.
A fossil remainder of this is still in the US default template: the Wall Composite definition "Wall Stud ext 2x6(6108)" for example is created to be corresponding to the WinEst assembly (guess what number:) #6108.
It worked with a predefined ELEMENT LIST from the calculate menu, exporting the text file - that was the file ArchiCAD import function imported in WinEST.
Later on we figured out a somewhat simpler interface via the COMPONENT LISTS and the WinEST GetElements menu command, where the line items were generated from ArchiCAD and imported into WinEST.
WinEST itself is indeed a user friendly functional equivalent to Timberline, with work breakdown, accounting interface, etc. and the comany itself is a goup of nice folks with dynamic agenda and good ideas, good listeners too.
There is a lot of folklore info about the ups and downs of the cooperation between ArchiCAD and WinEst, but that's not really interesting here.
IFC and Timberline somewhat seemed to have more marketing "pull", but IMHO WinEst was as good an estimator than Timberline (arguably easier to use), offered comparable or better databases (of course both of them offered the RS Means ones).