For the 'metrics like Visits or Unique Visitors that would get deduplicated' part:
Ok, so in Workspace, you might see a report like:
| |
|
Page Views |
Unique Visitors |
| |
|
10 |
3 |
| Pages |
|
10 |
3 |
| |
Page A |
4 |
2 |
| |
Page B |
3 |
1 |
| |
Page C |
3 |
2 |
So the "total" UVs is only 3, it's not 2+1+2 (5)... because the same user hit multiple pages. In the Data Warehouse, you don't get the de-duplicated total (or any totals at all)... So if you were to get this info in Workspace, and you total the data yourself, you would think that you have 5 UVs, and not 3... the more data you have, the worse the overcounting would become....
Page Views could even be impacted if you are using List dimensions, as each value in the list I believe is split into its own row... so if you have 20 items passed in a list on a single hit, it might look like 20 PVs in the Data Warehouse...
Understanding the format and frequency is something for you to consider, and when you have a better sense of that, I'd be happy to discuss some more specifics of the options (and lots of other people here would too)