The issue with some of the flavorings is that the can be a bit one dimensional compared to real fruit, but many people who have tried strawberries have said they are tricky to get the flavor they are looking for out of it. That being said, many fruits when fermented don't retain the flavors of the raw product. For example, wine tastes like many things, but generally not straight grape juice.

If you're near milwaukee, you should check out a beer barons meeting

http://beerbarons.org/

If you dont know any other brewers in the area, but if not and you want to go to a meeting, shoot me a PM and I'll give you the details.

I did a 10 gallon batch of chocolate-strawberry milk stout and split the batch with just strawberries in one and strawberries and strawberry extract in the other. Both were very faint in the strawberry flavor, although I got quite close to what I was looking for with the extract included. For the berries I used a 96 oz can (split in half) of Vinter's strawberries from the wine section of my Local Homebrew Shop. Then in the second batch I added about a half teaspoon of the extract to 5 gallons. If you're going with fresh berries I would go in the secondary and go big...Also as Spider mentioned, quarter and freeze first...I'm going to say 3 pounds...maybe even 5. The problem you may get is fruit haze, but if you're doing a wheat beer good chance you'll have a haze anyways but something to think about if you were going to try any fruit in say a light ale...
Cheers mate and thanks for your service!