Vin Rouge.
The fact the watch keeper is roughly the same as the Hermes is another point altogether to its cost. Some of the additional capabilities are very necessary for UK/Western Europe ops, but there is one major flaw in your post IMHO.
Watch keeper is an army asset while predator is an RAF asset. The watch keeper is flown by soldiers will basic instruction while the predator is flown by a pilot/aircrew. As the Royal artillery will only gave soldiers and not pilots to fly the watch keeper mission then NO a predator wouldn't be much help
