I'd try the recipe as intended first, and once you rack to your seconday for aging, taste test it. See if the strawberry flavor suits you. If not you could add a strawberry extract to the secondary or even at bottling if you want to.
Adding the strawberries to the secondary will give more intense flavors for some things. This however will not raise or increase the flavor very much. However, I would say that trying half of the strawberries in the primary and half in the secondary might work okay. Remember that the fruit just needs to have the color and the juices extracted. Having the must sitting on the fruit too long will start to impart bitter flavors. You will see that the strawberries get white after a few days.
This does have a nice nose with noticable strawberry and banana esters. Theflavors are there also but nothing is overpowering the other. I also would suggest you try it like it is and then go from there. It is worth sticking to this recipe!
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