Yes. Some months ago, I forget whether it was v5 or maybe before, the 2 button grading approach meant that it actually performed better for users (ie. it performed better for users that explicitly only used two grading buttons).
I don't know if this is replicable with v6, or not. I would be interested to find out!
I don't know if this is replicable with v6, or not. I would be interested to find out!