Uck, I wouldn't do that. Just because it doesn't melt outright doesn't mean flavors aren't coming out of the plastic.
+1 on that. I believe HDPE is only rated to 180. I would let my wort cool to 180 before moving to my fermenter when I was using Winpacks, which are HDPE.
P.S. I store my grain in my winpaks now. Seals up nice. Hard to get the grain in them. Easy to get out tho.