Hmm, if you don't allow customers to reduce size once it has been used once, that's pretty customer-hostile, especially with a metered service. Salesforce does not do that. Salesforce does, however, calculate used storage per sObject as the maximum size each sObject could be, based on each custom field, times the number of records. So, they definitely pad it in their favor per record. Also, Salesforce is transparent in their documentation about doing that, and suggests making fields only as big as they need to be, which is good governance. If there is padding in NetSuite's calculations, they are not transparent about it, which I take issue with.