Question about Hanna's Grow With Me Snapsuit

Does anyone use these?

They say that they have an extra set of snaps to grow with the baby.

Sooo....Autumn is in a size 70 right now and they are roomy on her. I'd be interested in the snapsuits for fall and winter. Should I buy the 70s and then grow to the next snaps as winter progresses? Will the 80s be huge still in fall?

She'll be one year old in late September and was 50th percentile at her last checkup.

I have one because I wanted a specific color to match the bunny wants a carrot overalls. The sets of snaps are maybe 1/2 inch apart, so I wouldn't count on a lot of grow with me room. If you want something for fall and winter, I would be tempted to get the 80.