Convertible mini crib vs convertible crib?

We are having a second baby- 14 months younger than our first. I anticipate my son will still be in the crib (maybe updated as a toddler bed) when our new baby needs to move into a crib. So, we will need another. I am between a mini crib or a full sized crib, convertible only because I like stuff to last. I would like them to share a room and potentially have to option to move the second baby between rooms so the dimensions of a mini crib would work better for that to avoid being overcrowded. However, I worry, that even if the baby is in a convertible mini crib they will outgrow it too quickly. However long was your baby in a convertible mini crib? When did they outgrow it? Answers I found online ranged for 1 year to 3 years so I am looking for some clarity.