It is hard to not use plastic vacuum bags for sous vide. Although there are re-usable silicon bags, such as stasher, they are — personal experience here — not very good for sous vide.
Yes, I too have used a couple of different silicon bags as alternates. The stashers are barely usable, and the cheaper but more sous vide friendly are ok but are hard to clean if you're trying to reuse them. But is it about the heat transfer and stable temp, so anything that keeps what your cooking completely in liquid and can tolerate thermal expansion should work, right?