I suspect it comes down to training. If an individual solder was trained on the No1MkIII and then handed a rifle with a totally new sighting system I feel that he would of course prefer the No1MkIII. As for the bayonet I’m sure the 1907 has much grater intimidation factor but I can’t imagine trying to use a No1MkIII fitted with one in any tight area like heavily wooded areas or house clearing. The No4 is already a bit long for ether of these jobs but in times of war you use the weapon at hand and if a Sten isn’t available…….
Just my 2cents