Despite LolaBunny's mockery and closed mindedness, TFES is actually open to all theories, both conventional and alternative, to describe the physics of the Earth and the universe.
The question as to what would it take to convince me that Earth is spherical is a little hard to answer. It would be like me asking you what it would take to convince you that red is really green. You could try to convince to me that the moon landings were real, I suppose. Or, you could prove to me that the government has never lied to me. I really do not know for sure what would convince me of anything that I have not been convinced of before now.
Going into orbit, if possible, would definitely be fun though, no matter how unlikely. However, seeing only a portion of the Earth would not likely convince me that the Earth is a globe, considering that it is common knowledge that only a portion of the Earth is lit by the sun at any given time.