This is an old thread but my 15 weeks DS is exactly like that. He hasn't slept through yet but if he isn't swaddled he would with startle himself or worse try to suck his hands and work himself up. So he definitely sleeps better swaddled.
I have tried very large Muslim wraps but they don't work anymore. I tried the Halo sleep sack and his arms still escape but he screams when I put him into it. Now we are back to the love to dream swaddle which he likes but I must wrap his arms by his sides using an extra Muslim cloth before putting him into the swaddle, or his arms go up and he starts trying to suck them. If I don't use a Muslim wrap his hand can even wriggle out of the neck opening!
i am thinking of the woombie or the ergococoon but not sure if its a waste of $$$ cos he seems like he's going to roll over soon. Anyone has bub's hand wriggle out of a woombie or ergococoon?