Well, let me say some things I think from my observations of U.jamesoniana in its natural habitat.
First, lets not mix species from section Iperua and Orchidioides as they grow in different conditions.
I think the plants form section Orchidioides can be easy or difficult depending on the elevation the plant comes from. For the highland species like quelchii, unifolia and campbelliana a good drop in temperature during the night will be needed. Without it the plants will grow slowly, become weaker and dissapear in the long term.
Species from lowlands like U.alpina should be easy and fast growers.
Last week i got plants of U.jamesoniana from two new locations. One i collected at an elevation of 1100m (3600ft), can be considered a lowland form and i hope it will grow easier than the first form i got. My father coincidentially found another plant when he was collecting some sphagnum for his ocrhids. The plant from an elevation around 2000m has more purple colored flowers but might be harder to grow. time will tell.
About the dry dormancy requirement, what i have seen is that all habitats will have a drier period with less rain when the plants will get dry but the important thing is that relative humidity will always be high by the presence of nearby water streams or the presence of night/morning fogs.