In terms of difficulty, I'd rate the carpets easier than rainbows, but not by much. I've heard a lot of talk that carpets require relatively high humidity like many boids but I've kept my hatchling in a 10 gallon (screen top) without any problems whatsoever. He's always hungry and hasn't had any shedding trouble at all. I mist about once a week but thats all I do to regulate humidity.
The BRBs do require higher humidity, but I've found that providing them with a "wet" hide, such as a glad/tupperware or small rubbermaid filled with wet sphagnum moss keeps them happy. I keep mine in rubbermaids in a shelf/rack system and so ventilation is relatively low and I also mist or spill water on the newspaper substrate once a week or so. The thing to remember is to make sure everything is clean. I change both the moss and newspaper every other week or whenever they defecate. I keep mine at room temp (mid 70s) with a heated corner (80-83 high) and have not had any food refusals or shedding problems. They seem quite content.
Temperament is the great equalizer. While both my rainbows and carpet were nippy when young, the rainbows tamed down MUCH easier. They still bite on occaison but its very rare and usually I can tell if they are getting upset before it happens. The carpet is just nuts sometimes and will strike anything that moves. I hear they grow out of it with time and age but handling hasn't seemed to calm him at all.
Van