I would say if your daughter does well in her crib, isn't and goes to bed well, she should do fine on a mattress on the floor at 17 months.
My son was in a toddler bed by the time he was 20 months old, just because I was so pregnant, I couldn't bend to get him in the crib. He did well wiith bedtime and didn't try climbing out of his crib, which is probably why he did so well in a toddler bed, we've never had problems with him getting out of bed.
I would think that's the only risk if she moves to a mattress or toddler bed, the fact that she may try to get out of bed at bedtime...but if you approach it the same way each time and just put her back in bed, it probably wouldn't last too long.