Blasphemy! Lol, jk... But seriously 3 different configurations give all 3 rifles a different feel. C7 clone = fixed stock, 20" barrel, elcan optic... M4 = adjustable stock, 14.5" barrel, Aimpoint optic... AR PDW = adjustable stock, 7.5" barrel, reflex sight, 300 BLK...
As for the Tavor vs PS90, I'm torn, PS90 is common in video games and TV as such makes the younger crowd wet, I dunno.. We'll see...