Hi Dess, what you read is right. Urea is potentially a very dangerous chemical for orchids only when you consider conventional growing. I fertilize my orchids with urea but only as a foliar spray at the rate of 75 ppm (75 mg/litre). Urea is bad when used at high doses (^200 ppm). Urea at 75 to 100 ppm is beneficial for orchids and most plants. One of my friends in the orchid industry tells me that it is a ingredient of the foilar spray they use on Phalaenopsis, which makes the plants grow and flower about 30% faster. Just avoid using it as the sole source of nitrogen.
If from the 300 mg nitrogen supplied by 1 gm of your fertilizer, 100 mg is (~30%) is from Urea then it should be just fine.
But urea is a strict NO if you are growing your orchids in Semi hydroponics or in a completely inorganic media.