Toddler bed.. when?

When did you ladies transition to a toddler bed?

My son is almost 2.5 and im thinking its time soon.

But.. the toddler beds look so high still, even with railings? My son moves alot in bed.. wouldnt he fall off?

I was thinking maybe something like this since its closer to the ground?

Im mostly just afraid of him falling!

Also, do you need a new mattress or does the crib mattress usually fit?