My standard practice is to type a reply like this, then let it settle a while before posting, to prevent a hot reaction from being forever available on line. In this case I'm making an exception.
Crap.
Ebony cameras are neither overbuilt nor under-engineered. They're extremely precise and well made, probably the most so of any wood cameras available. Weight specification of the wood 5x7 Canham is 2.72 kg; for a mahogany SV57 it's 3.0 kg. Hardly "Rolls Royce tubby." Ebonies are expensive primarily due to extreme cost of doing business in Japan and the use of titanium metal parts (which probably also accounts for the small weight difference). After years of holding my tongue in this type of thread, I finally "let it all hang out" here:
http://www.largeformatphotography.info/forum/showpost.php?p=306668&postcount=3
While an SV57 costs nearly twice as much as a wood 5x7 Canham, I bought the Ebony. There is no reason to doubt what anyone says about Keith Canham's accessibility and responsiveness. For me, however, comparing products was ultimtely the best basis for making a decision.