Yeah, using the steps that one of the posters (erijohn) put up - It is a PITA....but more accurate, since using deal workflows to set date fields only works the first time the deal enters that stage. Once we are able to re-enroll deals in workflows then this way will be just as accurate, and infinitely more accessible.
HubSpot does a good job of reporting Time in Stage (after the deal has moved out of the stage) in it's own reporting system. The only reason I needed to pull from the API was to find time in CURRENT deal stage.
Sorry I'm very new to hubspot and am self taught on all of this. Where do I go to set the date stamp property? I can't find the option when I'm setting up the workflow.