Okay, so the fact that its leaked (as opposed to released) from Samsung explains why it isn't hosted on a respectable site.
Again, I'm not used to the Micro$oft side of things, but it seems to me like running some binary you stumbled across on an unknown website might not be the best of ideas. Do Windows uses ever get computer viruses ?
How hard would it be to write a program called Odin that grabs your IMEI, sticks malware on your phone, or maybe just "accidentally" fails while writing your bootloader ? How do you know that the latest random "Odin" binary you stumble upon on the web isn't exactly such a program ?
One of the great things about open source (besides the price !) is that you (or at least somebody somewhere) knows exactly what you are getting. I haven't actually used heimdall (no affiliation with author) but I'm surprised that this or some equivalent open-source approach isn't more widely used amongst the xda crowd.
I guess that even with an open-source flashing program you still need the binaries for the bootloaders, the pit file, and so on. But (as I understand it) at least in theory you could legally, safely obtain these from your own phone before you start flashing stuff.