I have kept both blues and ridleyi, but my experiences may differ widely from others. My blues were quite docile (I don't recall ever getting bit), and seemed to be very temperature tolerant. I could either brumate them with the rest of my colubrids, or keep the daytime temps warm and breed them throughout the winter. I'd estimate the length of my adults at just shy of 7 feet. All in all, a very easy species to keep provided you have sufficient room for them.
I currently have four adult ridleyi, and their temperaments vary from quite psychotic to mildly nervous. Their sizes vary from 5-6 feet (Cameroon Highlands locale) to nearly seven feet. They do seem to be more intolerant of high temps and will coil around their water dishes if it gets above the low 80's. They are shy, and spend most of their time in hide boxes (imagine that -- cave dwellers!) They seem to need higher humidity than the blues, otherwise they run into shedding difficulties.
Feel free to email me if you have specific questions. I no longer have blues (kept them for three years or so), but do still keep and enjoy the ridleyi, despite the occasional bite.
Happy Holidays,
Ronda
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Ronda Van Winkle
Northwest Herpetoculture