With the ALCl4(-) and FeCl4(-) anions, you have to avoid contact with water. HCl will be generated.
The BF4 and PF6 containing anions are safe, but especially the PF6 anion can generate HF at higher temperatures. We have no experience with PF6 containing ILs
We have used [4-mebupy]BF4 at 80 °C during a prolonged time in our pilot plant, and we did not see any sign of corrosion in our equipment. The IL remained stable, although coloration occurs.