... and after all that I did not actually answer your point... whoops

the asset I create in xara is for those things that do not have to be given the 'windsor and newton brush treatment'; think backgrounds, buildings etc - its all vector at the end of the day, too much detail can be the kiss of death for animation, any form of cartooning in fact

but what the brush enables is spontineity and sketch [in the sense you defined elsewhere] - this gives punch to the foreground, contrasting with the background, bearing in mind we are talking cutout here