Added to this thread in order to share experiences on sealing bags, while I just started using mylar bags (food storage quality bags with foiled lamination) last year it has been a major win for me. If you will use the zip lock design (the ones without it are less expensive) and seal the bags just along the edge, even if you are using an iron, you can later cut across below the seal and still have the zip work when you open the seal.
Otherwise (if you stored a larger quantity than a week or so worth of tobacco) you can always iron it back shut again. I use quart or smaller bags in order to cellar a working amount of tobacco without having to reopen a large bag ( a point I picked up on the forum when I was using jars) It lets the chemistry lie undisturbed until you are ready to smoke most of the bag. The jars had quickly become burdensome, as noted above, as my cellar grew.
I ordered a few gallon bags with my original purchase and they held 5 round tins each. Probably overkill, but I did not have any other use for them after it all got going.
The mylar zip lock bags far out perform the plastic storage bags for temporary smoking storage also, in my home anyway.
When considering long term price increases for tobacco and the aggravation of discovering failure years later, the price of bags is relatively inexpensive. I cannot speak to storage condition yet but have no reason to doubt the results will be good based on the experiences of others so far. My decision to convert the existing jars in cellar to bags also did show the tobacco stored in jars had done very well for the most part. I had only started cellaring aggressively in 2013, so the jars were aged at most 2 years.