Having been following this thread for some time, I was interested to see that overnight @hubspot has enabled a new calculation for deal amount - that being a manual entry. This is obviously a positive addition, but despite this field being editable within the products section of a deal, it still can not be used within a workflow or be automatically populated by the margin on a deal.
Greater flexibility on financial reporting is a must for any business.
Please HubSpot - if the platform can calculate the figures your users need (and it can, as they are there for all to see) then let us use them for reporting, within workflows, to copy property values from one field to another etc.