There are a few disadvantages to using a vacuum sealer for packing backpacking meals and, IMO few advantages beyond somewhat increased storage life.

First, vacuum sealers require a special type of (pricey) bag, or at least the ones I have used did. Second, the bag material is heavy and not particularly abrasion resistant. Third, vacuum sealed meals compress into an irregular shaped solid and inflexible mass typically with numerous sharp corners. Forth, combining the second and third issues, any friction of bag against anything else will wear holes at the sharp corners breaking the vacuum. Fifth, because of the rigid and irregular shape, vacuum sealed food packs with far more air space than with more efficient ways of packaging.

My preference is to just use a heat sealer and the much lighter and just as robust (and much cheaper) sandwich bags. These weigh about 4 gm each compared with 10 gm for the vacuum sealer bags. There are 28.35 gm per ounce. And, you can heat seal a sandwich bag and then trim off anything outside the seal line. You can package, separately, different ingredients in the same bag by doing a vertical seal to create two compartments and then putting the different ingredients in the compartments. You can package a weeks worth of pills into daily packs with the same technique.

For storage, I add a small oxygen absorber pack. These can be purchased online quite inexpensively and add measurably to shelf life.

Finally, for packing into limited space, I poke a pin through the bag just before packing. This lets any air escape and reduces significantly the volume required per package. I rehydrate my meals in a roughly two cup Ziploc storage container that weighs less than an ounce. Using these techniques I was able to get 10 days of food into a Bearikade Weekender on my most recent JMT through-hike.