Although I rarely microwave Foodsaver bags, I've always routinely brought a large pot of water to the boil, dropped in one or two bags, and removed from heat. One or two pound portions are ready to serve in usually 15 minutes.
Never heard of any caveat against boiling water. Tilia's website says:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Prepare meals in advance. No time to cook every day? No problem. Cook one day a week, vacuum package and freeze. When you're ready to serve, just boil or microwave right in the same FoodSaver Bag. </div></BLOCKQUOTE>