the ideal layout in my opinion would be as following..
on the backend to have an option to select how many different slides will the slideshow have for instance 4..
then on each slide to be able to select specific articles,k2 items to fetch, so the slide will be consisted of the exact article/item tiles that the user has selected
for instance
slide 1 tiles 1,2,3,4,5 from articles a,b,c,d,e
slide 2 tiles 1,2,3,4,5 from articles f,g,h,i,j
background the easiest way to go would be colour selection or for more complex fetchig one image from each article..but also this could be easily modified by a developer through css..
more complex would be along with article/item selection to be image selection, but this would require extra work to be done..
i have noticed though several requests over the web for module with that particular effect, both in joomla and in wordpress..