What are the pro’s and con’s from the PR standpoint, from our standpoint?
With statehood they give up the option, equally available right now, of voting to become an independent country, with all the perks that go with being a separate nation. No doubt the UN would be glad to admit them as a full member and help them out with all sorts of goodies. They will also lose some concessions which they enjoy as a territory but will not as a state, tax breaks and the like.
If they vote for statehood, they are "going all in" with the USA. They have not wanted to, up until now; so I would wonder, why now? If I were a PR citizen I would vote for the status quo. But I'm not.
Politically, Islanders have a viable two party system. They are not like mainland welfare clients. It would be a mistake to write them off as automatic welfare democrats.
That's my off-the-cuff take, others may differ.