Some seem to have lost the plot on this thread !
Off-route in the UIR is only possible if the Montrose(ScACC) and London controllers are willing to take it upon themselves to co-ordinate against the military traffic, and speaking from the Montrose perspective, this is not a practical option except at weekends.
So, Chiglet, the option isn't there for EZE at their planned levels.
If, however the airline negotiated a service agreement with London and Scottish Mil, it may be possible to route direct, but always subject to their other tasks.
The route joining at SILVA then NEW-FINDO-ADN seems to work well and gives the paying passengers the protection of CAS all the way.
Finally the ADN-NEW-POL Airway is still very much under negotiation, and may well be with us in 2002(latest rumour).