ok well,
first off, many of the odors involved are organic faty acids, which is why they cling so well. and these odors have a halflife, most faty acids break down within 45 days in an oxygen rich environment. so ambient smell loss is to be expected, fortunatly many of the scent molecules stay fresh within the vegtable matter.
second, plastic is NOT an oxygen barrier. even freezer bags are only really a seal against larger h2o particles and CFC's. you need foil, or mylar.
the bags they ship computer parts in are perfect, and once heat sealed are as effective an airtight seal as can b achieved on the cheep.
third, oxygen is your real enemy during long term storage. yes moisture is an issue from a mold mildew standpoint, but once thats delt with oxygen is the main culpret in loss of smell and potency. a vacume seal while great, reduces the evaperation point of water, cuasing the internal moisture to turn to steam at remarkably low temperatures, which in turn reduces the vacume blah blah u get the idea, all this can overdry the bud, but its easy enough to rehydrate.
the ideal storage method in my mind is foil bags filled w NITROGEN gas, then heat sealed. nitrogen is very non reactive, and cheap, and non flammable. just dont breath it cuz ur body cant tell the diff between o2 and N, and ull die without realizing it.