I think the Speaker has been pretty consistent in rulings along those lines. I would leave it at that, without treading into an area where I wouldn't be comfortable. I think the Speaker has been pretty consistent in his selection and in the criteria he uses to select motions at report stage or amendments at report stage. Ultimately, what he judges to be an opportunity to have been presented at committee may vary, but he has been pretty consistent in his application of the rule that you've mentioned.
I'm sorry for the vagueness. I just do not want to substitute my decision for the Speaker's.