No one knows what Maytag/Whirlpool would have done, but I would agree that it would not have much different from what TTI is doing. But still, TTI has done some pretty bad things to the new Hoover name. For example, they have re-branded cheap DirtDevils into low-end Hoovers and shut down all manufacturing plants in North Canton, but I doubt much could have been about that anyway.
I think TTI machines are decent vacuums. Most are better than the Bissell and Eureka competitors, and the prices reflect the quality. Late Maytag Hoovers got pretty bad, like the bagless Tempo, so you will get better results with your Windtunnel Air. However, you can get much better vacuums at lower prices than the Windtunnel. The Eureka 1934 retails for $99, the Hoover Tempo(very, very nice Hoover)is $75, or a Hoover Elite is only around $100 brand new. So look at all the options for sure.