It's not so much what it will bring to the board as whether or not you feel it will give you a solid experience.
If you trust the company to be upfront with you and provide you some amount of due diligence, go for it.
Unless the plane ticket is expensive, I would kindly refuse their offer to fly you in, and instead pay for it yourself. The nature of your relationship changes once you start receiving compensation in kind for IR duties, and technically a free plane ticket could be considered such.