https://www.getleonardo.com/
Right now it looks very promising, but it do not reach the power of paintstorms brush engine. It simply misses the aspect of brush customization, nevertheless it makes some things better than paintstorm. For example it has a better simple designed Userinterface, which feels a bit like procreates but for desktop. And the speed of the brushes (without all these customisable parameters
) is awesome. You do not feel any kind of lags which the developer has solved with backround calculating. I don't no if paintstorm right now uses some kind of backround calculating but it's still lagging with big brushes, although the speed of small size brushes feels perfect.I know that the development team of paintstorm is too small and needs more programmers. And because of that the one guy developer of Leonardo Henning Tegen ( http://www.getleonardo.com/company/ ) could work together with you guys
. I think your goal of building a new application only for painters is the same like Henning Tegens. So maybe you both get in touch and build a software many painters are waiting for 
best regards Eric
