I'm only partway towards this, but I'll play, and I am curious to hear the opinions of people stronger than me as well.
When I was pulling 405: I'd say that 135 felt "light" but 225 was heavy enough that I needed to pay attention, and 315 was heavy enough to require some real effort.
Now that I'm pulling into the mid-500's, I think 225 feels kinda like what 135 used to feel like (i.e. barely any weight), 315 feels kinda like what 225 used to feel like (not really hard to lift, but enough that I have to make sure I'm set up properly), and 405 still feels heavy. Today, 405 is about the same % of my current 1RM that 315 was when I could pull 405, but in the "how does it feel" category, a 405 pull "today" feels harder (I think) than 315 felt back then.
That sounds about as clear as mud, but hopefully it makes sense.