Why can't you add a correlation engine on the receiver device?
Adding and running correlation engine on the receiver isn't the issue, it's when there's a fault it causes serious problems (it tries to keep correlating and can't cope leading to massive backlogs etc.).
We have effectively been told we shouldn't be running correlation on a combo VM.
OH really? We've got a GEN3 combo box appliance, it commits suicide when too much correlation rules are enabled.