Mom's giving custody to dad?

I am currently primary custodial parent for my daughter. Her father is non-custodial getting her standard visitation first, third and fifth weekends and one day during the week for two hours. We don't really go off the schedule, we just kind of go with the flow. He gets her a lot more than he should but lately I've really been struggling financially so it helps. I've been thinking of giving him primary custody just because he's more stable right now. Has anyone ever done that? How did it feel? Did your mom do it to you? How did you feel? I'm trying to think whats best for her. She is 4.