Hey, I've always wondered that too! I've always used food saver vacuum sealing for fish. But I've always wondered how much the mylar actually does to preserve food.

We LOVE our FoodSaver....we've only used it for freezing meats but, when you can take a forgotten, three year old roast out of the bottom of your freezer and it cooks up like you bought it that day...well worth the money.

If you're talking using the food saver for dried food storage then results are mixed.

I have one - I love it.

The bags seem like they would be puncture proof but some grains or dried vegetables will actually go right through after time - so the food that you thought was safe from oxygen isn't/might not be and you might not find out till later. I prefer the mylar and O2 method for really long term but still use the food saver for shorter term - eg.1 year.

One of the best things about the food saver is the jar lid attachment. You can fill a canning jar with grains, beans etc and vacuum seal the canning lid on the jar. I like this alot!! You can see it here: http://www.foodsaver.com/product.aspx?pid=9066

I have had a vacpac machine for 10 years! I LOVE THEM!
I just bought a food saver from a second hand store (Yes brand new and $10! I was so psyched!) and between my friend and I we have vac packed everything we could get our hands on this week.
I have done berries... all kinds of berries, veggies galore (I preslice and blanch veggies for soups and stews this way... just throw about 2-3 cups worth in the bag and seal it, pop it in the freezer), bacon, beef jerky, sandwich meats, left over cooked meats all in the vacpac and then frozen them... I have yet to be disappointed! I also vac pac rice or pasta (2 cups uncooked) seal, label them and put them into my containers in my stockpile.
Little spice packs, if I only have enough to mix about a tablespoon or two of spices, seal it into little strips. I make a mini vacpac bag. I take these with us up north for our camping, cottage and hunting trips.
Dried fruits, raisins, homemade trail mix, almonds (when they are on sale, raw no salt no crap on them) I seal them so they stay good! The longest I have tested is a year and they were great!
The possibilities are endless! It is a wonderful investment!

thanks for your input everyone, i will be getting a foodsaver system in the near future

Side note....if you save your Canadian Tire money....you can basically have free refill rolls. We buy bags once a year and buy the biggest refill pack CT has with the CT money.

i have one, i haven't used it much, the stuff i keep in the freezer stores well (a year) with just a zip lock bag.
i've heard others talk able using it for grains or other dried items.

anything with an edge will (sooner then later) break the seal. some have used plastic wrap to wrap it up first then vacuum seal with mixed results. one buddy uses the mason jar attachment and seals things like that in jars.

mylar (and i only buy the large ones) are great for long term storage. they are easy to work with, and stand up well. you will want heavier things to be in a bucket for support, but doing oats could be just sealed up then placed in a tote.