Putting it in it's own VM would allow to keep IE in a perfect replica of it's current environment (same OS, libraries, plugins, helpers etc), while securing it

Putting it in it's own VM would allow to keep IE in a perfect replica of it's current environment (same OS, libraries, plugins, helpers etc), while securing it from the outside (for instance firewalling, snapshot of valid states to prevent corruption, check on the data exchange on the network interface, sanitizing of the input/output if really needed)