Bethany I don't want to suggest that the toy (or any other stuffed lovey) is in any way unsuitable or potentially dangerous or anything like that so don't take this that I am suggesting that at all. But, I was much like you and was extremely worried and cautious about everything SIDS related...we gave DS a lovey sometime shortly after 6 months and I *think* I took it from him after he'd fallen asleep if I remember correctly, until he was about 8/9 months or so and was not just rolling, but totally mobile, crawling around his cot.
My DS also wanted to roll from about 4 months and was in the miracle blanket, but would get stuck on his tummy. He NEEDED the swaddle though - we tried a few times without and had like 30 minutes of sleep all night. He could not do it - even at 6 months when we tried again it wasn't happening. It was a slow gradual process to get rid of the miracle blanket finally at 8/9 months (when he was allowed to keep his lovey).
We did what Meditrina did - kept him in the Miracle Blanket and used sleep positioners to keep him from rolling. He slept even better that way than just in the swaddle. I'm all for letting him sleep how he wants to sleep and all that, but at the same time, I am also a bit overly cautious and tend to take the attitude of "just cause you can doesn't mean you're allowed to!" even when it came to what position he wanted to sleep in. In some ways I do think it's not "right" (ie/ to prevent him from sleeping how he wants to) but it was what worked for us AND kept me comfortable and content with his safety (after all, I need to be able to get a good sleep too!). If he'd had an issue with the sleep positioner and not liked it I would have had to re-think it I guess!