You are right that there is a large increase, but it’s not linear.
So, check for yourself with the simulator, the big chunk of increase if from 4000 to 4800 GB.
With your setup,
4000 GB --> 2600 TFT per month
4800 GB --> 3112 TFT per month
5000 GB --> 3122 TFT per month
8000 GB --> 3272 TFT per month
*Also, we must not forget that Zero-OS takes some resources. That’s why I said go with 5TB. It’s also good to check with your SSD if they say 5 TB on the specs, is it 5TB usable TB or the SSD takes some space by default to run. For example, 2TB is often 1.6TB is real world use.
This ratio is to optimized the 3nodes with potential Grid utilization.
So the compute units and in line with memory units.
It might change in the future if we find out be empirical means that it would be more useful.
The DAO will permit such modifications, with the content of the community.