I don't remember a "Viper". I do remember the pre-bagged days, when you could open (not to remove a part, else you'd not get things back in place) the kits and see the wood quality, the die cut sharpness (or not), etc. I built just one Circus King, from the terrible wood that PDQ used, which was worse than what Sterling offered. I can't recall the kind of die cutting that the Circus King had, but it really seems to me that the newest Ringmaster kit I ever saw, which would've been in 1952, I suppose, was already Sterling style "die-smashed".
Having given up on spark ignition 60s in 1950, my next modelling attempts were based on a couple of 09s, the OK Cub, and an Arden, both of which gave me trouble, but did keep running more than a half a lap (no one told me back then about the need to move the spark advance after starting -- I didn't know any adult modellers my first two years of attempts). I built several Enterprise and Scientific kits for those 09s -- the only one that flew moderately well was named the "Slick Trick".
Comparing Veco kits to Berkeley, PDQ, and Sterling, the quality difference favoring Veco was obvious to anyone willing to pause and actually LOOK. I built those when I finally got a first "big" glow engine, a Torp 29 (and when I could afford the cost of the kits). Tomahawks, Warriors, Braves, I loved 'em. I probably built more Circus King scratch builts at the time, because they were somewhat simpler, with fewer parts, than the Brave or Tomahawk. I never scratch built a Tomahawk to the same design as the kit, modifying my scratched versions into something closer to what the Dumas version would be, years later, with only two spars instead of about four.
Oh, well, the question is would I go back? Not to the hardware of the day, no. But to the spirit and the patriotism and the enthusiasm that even older people were feeling then, in spite of the "Cold War"? Yes, I most surely would do that!