Pearwood is extremely dimensionally stable once it is dry and is quite strong. French Pear is one of the names for European Pear (a name common in the U.S.) ,pearwood (a common name in the U.K.) or Common Pear. They are all from the same genus and species therefore all the same.
As Nick has pointed out, most orchard trees do not get that big. The lumber yield from branches and trunks of orchard wood is usually very low because of distortion during drying. The wood should be kiln dried and then machined several times before reaching final dimension. There should be a rather liberal time given between machinings to allow the natural stresses in the wood to warp the hell out of your nice flat lumber. Then it can be machined and warp again. So what you are left with when you finally get it straight is very little. This in addition to the small branches you start with makes the yield very very low and therefore the price is quite high.
According to "the Real Wood Bible" (best book I have ever seen on wood) Pear is medium hard and rather heavy at 44 lb. per cubic foot which is more dense than Black Walnut but less dense than Red Oak. I suspect it is stronger than either and it is more stable dimensionally than Walnut or Oak.
So I guess if you can afford it, it would be an excellent wood to make cameras from. It certainly would have some snob appeal.