There was a time that many of the skiers here can remember when 70mm WAS a powder ski. Two powder days in my life come to mind when I think of this..actually three. First was about 1981ish at Camelback in the Poconos. It was a rare powder day, real powder, light weight not just the heavy snow that the Poconos were known to get. The one run that comes to mind was skiing the Bailey Chair lift line top to bottom on my 195cm Rossignol ST Comps. The run was light and effortless, that ski was maybe 66mm underfoot. I am not sure
@Andy Mink was there that night or remembers it.
The second time was the first year we moved out to Tahoe.
@Tricia and I were at Northstar and it was dumping to the tune of 4-6" an hour. We ran into
@cbk that morning when he was talking a clinic with Mike Hafer.
@Tricia and I took off and skied the Martis Camp area and just did lap after lap on basically the same line. As the day went, early in the AM, stuff that we were dropping off of, later in the day we were just rolling off of. That day I was skiing on the Blizzard Bonafide, not relatively wide at 98mm underfoot.The last one that comes to mind was at Steamboat a couple of years back. A group of buddies from the east met
@Ron and I there. That day I was on the Renoun Z90, not as narrow as the OP suggested but not wide either. Again it was champagne powder, light as light can be.
If given my choice I would rather be in the snow than on it. So when in powder I will tend to be on a narrower than average powder ski. I rarely get on something over 115mm and I am usually on something 100ish. Granted it is not the 70mm requested but if I was to get on something in that range, as much as the width I would be looking at would be the flex, if the skis bend easier, it will be more enjoyable in the deep.
This still comes down to the right tool for the job too, some might prefer an open end wrench, some might perfer a socket, some might prefer a drill with a socket attachment and some might prefer to pound that bolt into the wall with a hammer.