Keeping with experiments, I heard Badger Stynylrez Primer can be brushed too (
https://www.youtube.com/watch?v=CVDJrF7fNp8 or
http://amps-armor.org/reviews/showRevie ... TR&ID=3088), but it seems most go with airbrush (still looking for a real brushed demo, not just "yeah, you can"). In the list of things to test because Vallejo Surface Primer range is meh (no sanding if you want to stay sane, peels easily when using masks even after days of curing, poor adhesion to metals in general, etc) and so is the no brand name gesso I got (works fine over wood, paper, etc... must be "classic painter" only).
BTW, in other page of DecoArt site they say their Ultra Matte Varnish can be used as base, but I fear it could go as VSP. Badger products are harder to track locally, at least Americana paints are avaliable (not so the Adhesion one, but I think I saw the Sealer and the Varnish).
So 1 by Badger and 3 by DecoArt. Oh, I forgot, also the Mr Surfacer ones, but those need nasty thinners and cleaners, so way down testing list.