I've built a few of the John Rendall plaster buildings but have never tried the DownTown Deco kits although I have seen them and they appear to be very similar.
The only problem I recall was squaring up the mating edges and surfaces. To get them flat and square I glued a sheet of 400 grit emory paper to a piece of glass and would then rub the various pieces across it to get the edges square and the back surfaces flat to make tight fitting joints. I used white carpenter's glue to glue them together and they were quite strong. Any clean up around window or door opening was easily done with a sharp Xacto knife.
I would not reccomend painting these kits with any type of water based paints. I used regular Floquil to paint mine and they turned out great.
Hope this helps.
