Thanks for the tips. I've had the Scorpion ATRs now for over a year and 15,000 km. I've taken them on multi-week expeditions to Sumatra and Nusa Tenggara. For what they are, a relatively non-aggresive AT tread, they've been great. For my next expedition (Celebes/Sulawesi), in 2010, I intend to put MTs on it, most likely the Toyo OpenCountry.
No, I do not go on overland expeditions during the rainy season. The rain presents problems not only for wheel traction, but for other ancillary activities during these trips such as camping, hiking, mountain biking.
Here are the Scorpion ATRs out on an overland expedition in Sumba