Online reviews are a bit mixed, some suggesting that the heel area can cause blisters due to the multiple layers of fabric, but for my 7km trial they were fine. The sole is definitely not intended for road mileage and probably designed for short course obstacle races and fell runs. They felt secure on the leafy, muddy tracks in the woods. On tarmac they were squishy and I could feel the lugs moving underfoot although I never felt any slide.
The heel drop is reputed to be around 6mm so on the low end of my normal range and on that basis it's probably sensible that I elected not to wear them on last week's event. They would have been great on the heather and peat but perhaps hard on my calfs on the frantic last few km.
Another nice aspect is that the uppers are clearly broad and not tapering, that is more foot-shaped than many shoes. I'll have to see how things go over the next few runs but today they didn't dig in around my heel even though I made a fair pace and had to adjust my feet as I stepped through autumn leaves onto the uneven terrain underneath.