Good practice to use NativeWebObject with browsers other than Internet Explorer?

The NativeWebObject.Find method should be available in any browser's Page object, and it should work with all of them. This is a 'global' method which isn't browser-dependent, and it is safe to use it. However, I wouldn't recommend using the NativeWebObject namespace (except for NativeWebObject.Find) with browsers other than IE. This namespace was originally added to resolve conflicts between IE's properties and methods (such as name or id), and this can make your tests IE-dependent. Since properties and methods added to this namespace do not depend on TC, but are taken from the browser, there's no guarantee that they will be there in all cases.