Millions of homes have pvc pipes, and they work well. What you'll potentially notice is if you convert to pvc there, the pvc will be noisier. If that is an issue, then pay to have it replaced with CI. It isn't that much noisier, but it depends on the construction. If that area underneath isn't something like a bedroom or the living room, no big deal - do it yourself with pvc.
To make the transition, you have two choices...remove the CI pipe from the hub and use a donut (Fernco makes some) with the pvc inserted in the middle, or use a no-hub banded connector on the existing stub of CI. This is a neoprene rubber sleeve with metal reinforcement band around it, anchored with hose clamps. The all rubber ones can't be legally used except underground.
Both are 'right' by code, would work well, and last a long time.