We have found out both times.
With our son I considered staying team yellow for a few weeks in the beginning as we had no preference over gender. In the end though, we did find out because I didn't like referring to the baby as 'it'. I wanted to know what we were having so I could bond better with the bab. Finding out it was a boy, giving him his name, imagining what he would look like and what our lives might be like when he arrived, making crafty things and clothes especially for him, preparing his 'nursery' (half of our bedroom)... all of that made everything so special. It wouldn't have been the same if I was having to make/buy neutral things and imagine everything as 'if it's a boy' or 'if it's a girl'. I loved finding out with him.
We found out again this time, but not to help bond as after having my son, I know what the mother/baby bond feels like now and already feel I have it with the baby I'm carrying. I couldn't imagine it before and though I loved my unborn son, I didn't know personally what this bond felt like, whereas now, because of our bond, I can extend those emotions to this baby as well. We found out this time because we were leaning more towards wanting a girl as we both want to experience having a boy and a girl. I wanted to find out what we were having as I would have hated to feel even the tiniest sliver of disappointment on the day my baby was born. I love my little boy to pieces, I couldn't love him any more than I do and had this baby been a boy, I would have been delighted to have another son to adore, but I do know I would have felt a tiny twinge of regret that I didn't get to experience having a girl.
We want three children. I have absolutely no preference for what comes next. With our son and expecting this little girl, I absolutely don't have a preference for whatever gender baby completes our family. We're going to stay team yellow the next time to experience the surprise. I imagine it's wonderful to find out when the baby is born.