Here are the PackitGourmet bags I was using in the past:
They claim to be safe, so long as the bag isn't dunked in boiling water (they have bags for that, too, methinks). Now how *safe* are they really? I don't know. Presumably, *some* plastic is going to leech into the food.
But again, the primary reasons for me moving to cooking in the pot are:
(i) to avoid eating out of a bag
(ii) to save weight.
On a trip which involves at least 3-4 meals (for two), it seems that an argument could be made to defend the claim that there is no weight benefit to doing FBC instead of bringing a bigger pot. A 1.3 L Evernew pot (including lid, apparently) is 4.6 oz. This is about 1.75-2.0 oz more than my BPL Firelite 550 pot. But the weight of the bags alone may come close to equaling that. If so, I'd prefer to take the bigger pot. Just package meals into lighter weight plastic or put multiple meals into one bag and aliquot as needed (may need a measuring cup for this purpose).
A final motivation for thinking about moving to cooking in my pot is that one can do real cooking. So for those times when the food didn't fully rehydrate it's easy--just turn the flame back on (especially if using a gas stove). If doing it FBC-style, you have to sit there and wait and hope it did reconstitute properly.
Now if I'm going SUL style solo, then perhaps I'll bring my Firelite 550 pot and do FBC style. But for those other times, I might try cooking in the pot (at least as an experiment).