Well, 60s roundies have a coarse phosphor dot pitch and relatively simple tube circuits... my 1976 Philips K11 daily watcher instead has a tank-like solid state chassis with about 50 transistors and 20 ICs, an electronic tuner and an inline CRT with a really fine phosphor stripe pitch and produces a bright, crisp, wonderful, absolutely noise free picture just like a brand new PAL set... i can't really ask for more...
I'd like to see the picture quality of a 31 yrs old plasma... but there will probably be no surviving plasma sets 31 years from now, especially in working conditions... while my then 60 yrs old Philips will probably keep kickin'ass with its original capacitors
Francesco