I think it's narrowing it a little bit, but not very much. I think the standard is problematic, and that's why I think either of the other options would probably be better.
I think it narrows the defence by allowing a chance that the Crown will be able to meet its burden and deny the defence to an accused in a particular case. I still think the Crown is going to have a lot of problems with any standard, given the things we've seen in cases like Daviault, Chan and Sullivan.
I think it gives the Crown a bit of a better chance, but getting rid of it gives the Crown a better chance.