I've just come back from Mulu, where I used the boots hard - I was there for 14 days, and caved on ten of them - three day trips and two camping trips, for three and four days. I've also used them on about six trips in the UK, and two in Mexico down the 450m streamway to the very big Muneca cavern, as part of Badlad's laser scanning project.
I'd say they are simply fantastic to cave in. Incredibly light and comfortable, even after several days' wear. Good for walk ins, too: lots of ankle support. In a guano-affected area such as Mulu, the drawstring gaiters keep the muck out. The sole grip on rock is superb, and even on mud it's not too bad.
The only drawback is that they are not made to last forever, or anything like forever. The toe protection where the sole rubber curves up is worn away on both feet, although I have added a layer of thick glue to prolong the boots' life. One of the eyelets has come off.
Then again, it was evident in Mulu that they are MUCH more durable than Five Ten canyoning boots, and that they offer more protection for the feet, too. The grip for climbing is way better than any Wellie. I've been wearing them with Sealskinz socks, even in Britain: a very good combination, and my feet haven't got cold.
Overall, i'd say they are the best footwear I've ever used underground, and when the current pair does wear out (still some time off) I will buy another pair.