well.....i flew md-83's for 5 years, and let me tell you.....they do have slats. they are normally extended manually, although they come out automatically as a last ditch attempt to avoid an impending stall. they are hydraulically powered, and they decrease the stall speed when used alone by about 30 kts.
the first position of flap selection is "flap 0", which is half slat extension, and no flap. when the trailing edge flaps start to come down, the slats go to the full extended position......and, yes, i do think slats would make a big difference on a model
virus.