My son loved being swaddled too. I would say take his lead on the swaddle. For my son, we swaddled him until he was 5 1/2 mths and around that time we began swaddling him with one arm out and then eventually both arms out.
I bought him the miracle blanket (if you google it, you can find the website and buy it online). It's a bigger swaddle and worked really well.
I think it was around 6 1/2 months that we were able to put him to bed without the swaddle completely. As I said, just take his lead on it. Some folks made me worry about swaddling him when he was 5-6 mths, but it wasn't really a problem for us and the transition was a lot better because we followed his lead. Definitely try the one arm thing and then two arms out. He'll still have the comfort of the swaddle across his tummy even though both arms are out.
Hope this helps.