Half the price of Fable 5 and useable with 100% of your subscription means roughly 4x the usage using Opus 5, presuming similar token use for solving problems.
Not that they should get credit for giving you only 50% of your plan worth of Fable usage but still.
There is a expiring soon 50% boost to your usage limits, so I think its 2.7x not 4x what you are seeing right now. I think, but its convoluted :)