been using 5-gallon with gamma seal too.. gotta put my vote for that one. Easy to automate burping with a pump, tubing, top-hat gasket and a couple check valves. even if you don't do that, burping 1 or 2 buckets instead of a shit tone of quart mason jars or even 1-gallon mason jars is heaven by comparison. From what i read this type of storage and similar won't lose much potency in 12-18 months but starts to speed up after that. Longer storage requirements should definitely invovle colder storage temps (and tighter packaging i guess would help too?) And, at all times should be kept dark, regardless of method... the jar you keep out for smoking that lasts a few days or a week before refilling it is not a concern, obviously... but over a longer period of time light is the primary enemy for potency.
if it smokes fast, it doesn't really matter much :P