I am not sure what you are seeing in those designs that makes you think they are so great. The only positive is that they should have a lot of displacement for the given footprint. So you have four 10"s in a cabinet with just 300 watts for the whole deal? I'm guessing those don't have much in the way of a motor. Contrast that with the Monolith 10" motor which is nearly as big as the cone itself:
The Tekton woofers probably don't have much in the way of excursion ability and likely have a relatively high Fs for a subwoofer driver, especially compared to "crappy" subs like the Monolith 10". They probably have a lot of output ability above 60Hz.
The thing is, for a subwoofer with a high Fs to have low bass in a sealed enclosure, you would have to EQ the response. In doing so, you majorly jack up the group delay, and I guarantee you it's going to be a lot worse than this "crappy" sub:
Here is something else to consider: if I asked Monoprice to send me a sub in order to test it to make the performance measurements public, they would have any sub I ask for on its way to me by the end of the day. You think Tekton would react the same way? Monoprice wants public exposure of their products' performance because they are confident in their products. There was one reviewer who attempted measurements of a Tekton review product that turned into a debacle with Tekton, and as far as I know, that review was pulled down.