As someone who swaddled for about 7 months, I personally wouldn't go cold turkey! I also have the miracle blanket, and it worked great, but he got too big for it.
I weaned from the swaddle by starting with one arm out (he used to suck his thumb around 4 or 5 months - he's since quit). I did that for a very long time, then moved to two arms out, so the blanket was just wrapped around his body and feet. At that point, it wasn't so much a swaddle as just a blanket I used to keep him warm. Then, I finally switched him to long sleeve footed pajamas, and got rid of the blanket. He never knew the difference at that point, as he was rolling and crawling all over his crib anyway, and the blanket didn't stay put for long.
HTH!