Peter,
Absolutely, but I wasn't comparing a 5 with a 6, except to say that with a limited n=1 experiment my 6 doesn't seem to suffer from the No5's problem. Granted "... extra ammo, water and rations. Your only re-supply is from the air..." so the point I was making was that having a rifle with some weight shaved off, a No5 or 6, would be preferable to a No1 or 4. Every little helps, as they say. And the bayonet was that bit lighter than the 1907 pattern too.
Regards
Ian