How I work a merge is this:
First, I adjust the date of the newer story (as it's normally the one being updated) to the original upload date. Then, I transfer the reviews to the one story from the other. Finally, I add in the rates that were recieved on the other story as well. Last step is deletion.
As to the workload, I knew, roughly, what it would be when I first started planning this repair. That's not to say I've not found new things that I need to do besides related to it, that weren't apparent until I was actually IN the db. .