I'm not going to advise you whether to vote for or against a union. That choice depends on so many things, about which I am totally uninformed that I couldn't give informed advice.
But here's what I know from having been in your place before. Take it for what it's worth.
1. The union will expend resources proportional to their chance of getting a favorable vote. If it looks like they are going to lose, they are going to cut back on the time and money they can spend to organize you.
2. Management will tell you a lot of things about the union that are not true.
3. THe union will tell you a lot of things about the management that are not true.
4. Both sides will make promises that they can't keep.
5. Both sides will make predictions about what the other side is going to do next. Usually, they are correct.
6. Both sides are going to accuse the other of violating the FLSA.
7. Both sides will probably violate the FLSA numerous times.
8. The union will tell you that you will make more money and get better benefits if you join.
9. The company is probably already paying you as much as they are ever going to.
10. Even though number 9 may be true, they don't have to keep paying you the wages and benefits you are getting now, and there is nothing stopping them from taking it away unless you get a contract.
11. Joining the union is the only way to get a contract.
12. Joining the union does not automatically get you a contract, nor does it guarantee what the contract will contain.
13. The union is going to make your bosses (some of whom are your friends) out to be a bunch of thieves living high off your labors.
14. The bosses are going to make the union out to be some kind of organized crime syndicate, squeezing you for your money.
15. Management will tell you that the union is an uninvolved third party who has no business meddling in the affairs between you and them, and that they will just make things more complicated and difficult.
16. Management belongs to INPO, WANO, EPRI, NEI, NANT, MANTG, and a host of other organizations who tell them every day how to run every aspect of their business - right down to how much they should pay you.
17. Both sides will try to make the other seem like a faceless entity which lives afar and governs in absentia.
18. The reality is that the company is you and the managment you already know, and the union is you and your co-workers. Both sides can and will reach outside the local "community" for resources if they have to.
You have to consider a lot of things. Are you a relatively small company (compared to Exelon, Entergy.. etc.) who is ripe for takeover by a bigger company? If so, they may want to come in and clean house. They may drastically change your job descriptions, pay scales, benefits package, pensions, an so on. In that case, a union affiliation may not be to protect you from your present management, but from the ones who come in and kick them out of their chairs.