Hi Simon
The question of which footwear is best is as old as the hills... and almost as old as me...
I struggle with high necked boots, especially on tarmac. They cause discomfort in my Tendo Achilles, and they seem to increase intrinsic foot cramps
I think the problem (for me) is worse if I fasten the top lace hole, or even the top two... Somehow I need my ankles to flex more whilst walking.
I also used to run marathons and sometimes greater distances, and if good road shoes are suitable for running a marathon, then the design must be part of the story. You don't see many folks running 26 miles in boots... ;). I understand that boots 'protect' the ankle, but from what I'm not sure. As far as keeping the feet dry, hmm, I'm not to sure about this either. Water goes in over the top and its in there for the duration. At least with low cut shoe styles, you can empty the shoe by flexing the knee. I'd rather keep my socks dry, but some terrain just makes this high on impossible.
The other question concerns your increase in mileage. Did you say you increased from 11 miles to 17 miles... Perhaps your increase should be less than this?
It could be a combination of tightening the laces (to stop movement), which may have restricted your ankle movement, and your increase in mileage.
Fell runners dance about in Walshes or Innov8s, and mostly they manage OK over some quite big distances.
I guess its the Boots versus Running Shoes debate. If you are troubled with higher mileages with boots, why not try the Dartmoors over the longer distances? or perhaps plump for something from
here...