It sounds like the "feel" method is the most reliable for now. I used to think that really accurate weights would be a good way to tell what's in each packet but people are reporting so many extra and/or missing parts that the weight method seems doomed.
If anybody is motivated to keep a list of the packet code and contents for the bags they open, let me know and I will start a list. Ultimately, it may not tell us anything (as cardensb said, several packets of the same figure had different codes) but if we have enough data we may be able to "break" the code (if there is one
. )
Thanks to everybody for all the great comments on this topic!
Special note for my friend Hadoque:
X-Ray Specs or, if you are willing to spend just a bit more:
Video X-ray Glasses