Tor, I think that purple haze is not refering to thrust vectoring. Some time ago I read an article in Flight International that NASA was conducting flight tests with a DC 10 (because of obvious advantages from the no. 2 engine position) whereby the flightpath was controlled solely by adjusting thrust on the 3 engines. No flight controls were used. They were able to control the plane using a computer that gave "thrust requests" to the engines using input from the yoke. The idear was to have a backup in case the hydraulics failed.
BTW, 747`s have 4 hydraulic systems. Twice I`ve had one system fail on me (in a 744), but the only implication was a manual gear extension of body and nose gear. Nothing more serious, luckily. Both times the failure was caused by leakage.
I believe the Fokker 27 used to have pneumatically operated flight controls and gear actuating. The advantage being that a leak had less effect on the system.