My understanding of planting them "upside down" is that the root will curl over and the seed casing will bend up towards light but this process helps shed the seed casing naturally. I've had a seed casing not come off by itself and if you don't help it off eventually, the seedling will die. With this said, it's not like mother nature has a bunch of garden gnomes out there making sure seeds are placed "the right way" in the dirt (although that would explain the purpose of garden gnomes wouldn't it?).
Personally, I've tried germination several ways and the best way (and least risky) so far is to drop the seed very shallow in the soil, water, put in warm dark place for 4 days then just put the thing under your light. In a few days you've got a seedling pushing through the soil. No risk in breaking off the tap root. But hey...everyone has their favorite ways. Just don't over think it....we don't give Nature enough credit.