That's a pretty impressive result.
If they have a blog of their trip I'd be interested to read it.I guess the prime factor must be the amount of snow cover and depth on the route,although these dates were just before the early February Arctic weather spell and snow dump.
The time equates to 6 days 8 hours,or 7 full running days averaging 38 miles a day.As such I'm sure it is a record that could definately be beaten!
I think you are right Alan, although impressive I doubt the record will last very long, although conditions will obviously play a big part.
Interested in comparing it with my own PW, I noted the winners average pace which includes any food etc stops in between check in/rest points.
Leg 1. 45 miles - 12h. 11min = 3+mph
2. 61 miles - 27h. 21min = 3-mph
3. 33 miles - 17h. 22min = 2-mph
4. 40 miles - 21h. 03min - 2-mph
5. 40 miles - 20h. 00min = 2mph
6. 42 miles - 20h. 17min = 2mph
Making an overall moving hours average of 2.33mph
Total rest time at 5 checkpoints = 32 hours.
Going off that they probably did most if not all of their running during the first two legs, then the foot problems and lack of sleep set in.
Lets not forget though they would only have had around 7 hours daylight in 24 and try as you do to keep up the pace, it always drops during the dark hours.