andrei1989 said:a sling for hiking is a no go!
all that weight on one shoulder (imagine adding 1-2L of water, some snacks and a jacket and you have a 4-5kg pack)
As my post noted, I use a backpack for hiking stuff (size dependent on the length of the hike) and an M3 with two lenses in a shoulder bag. "All that weight" can not be a criticism of the M3!
Works for me but of course YMMV.]