I've always been a real stickler about what reloading data I use, mostly out of fear of blowing myself up. So I've stuck to the usual sources, almost always from the particular bullet makers manual.
Since I've been a long time subscriber to Rifle/Handloader/Hunting magazines I'm somewhat tempted to try Loaddata.com. It's not a fortune at $34.95 a year. What do you folks think of it? Does it offer anything extra?