As far as tracings, they definitely do not always work. I sent mine, and White's recommended 9.5D, but I had just tried that on and it was quite tight. Then tried on an SJ in 9.5E and THAT was tight. Ended up with 9.5EE, though I think in the SD last 9.5E would have been fine.
Hear hear. Whites first advised a 10D, and I ordered with them...I was floating in those...not even a thick hiking sock could correct them. I`m now fitting comfortably in a 9D. And guess what, I had to try the 9 1/2 at my own expense too...two sizes out! Not happy about this. Nothing better than a brick and mortar fitting.