I agree with you about the SPS. That's a good point, and I hadn't considered it until this post.
Just 'cause you got me curious, I checked against the closing prices on coinmarketcap. Here's what I found, where the price is between X and 1/X.
It is in that ballpark you described, but I also think it's problematic for the price to be outside the (3/4 -> 4/3) range for more than 25% of days.