When I first started planting trees, I thought it wasn't advised because the branches would snap from the weight. I grew a carambola on an espalier wire and since, it was supported, the young tree gave like 25 carambolas!! Man, did I think I had it figured out. Now, a year later, the tree hasn't even thought about blooming, yet all my other carambolas were. It's like a young teenager having a baby. She may be able to have a baby, but that doesn't mean it's best for her health.
It ultimately depends in your patience level, but doing it simon's way and providing the right nutrition for the tree will ultimately give a great harvest once it finally comes. That being said, I usually keep 1 fruit to try, and if it turns black or drops, so be it!