I think you're getting screwed dude. Engines have to be run hard to break them in. If someone told me that I had to baby the engine for 3000 miles, I'd tell them to piss off. You paid thousands of dollars to get IAG (the golden calf of the subaru community in the NE, lol, if you exclude andrewtech) to build this engine "the IAG way" and now they're telling you to limit your power output.
Did they take a dyno pull for a base run/ring break-in right after building it? You never answered on jabber.
It's curious that all engines EXCEPT for consumer cars, motorcycles, and trucks you run it like you normally would during break in. Airplanes, heavy equipment, generators, except for 2-stroke, you run as you normally would during break-in.