If you look around the forums you'll see many many different heated debates over flushing at the end. Pre-Harvest Flush Vs. No Flush is almost like a religious discussion. Both sides have very strong views. My best advice is if you have more than one plant, try flushing one and not flushing the other. Give them both the same dry and cure and see which you like better.
Personally I think it's just a myth that people blindly follow. I believe what my experience tells me. These forums are great for information, but in the end it's what ever works best for you. Your plants are gonna be different than mine, so what works for me isn't going to work exactly the same for you. Just keep in mind their plants.