The Harman paper did take the concept further. Nevertheless, multiple subs up front has alot going for it. Anytime I have heard subs with upfront placement it sounded very good, though the visual impact may have been a factor. I like his idea that "reflections from the side walls will continue, creating a line source of infinite length". It helps explain why that placement always sounded good.
With duals in the corners, its more hit and miss than suggested in Ohman's article. It can contribute to boomy bass from reinforced peaks, especially in smaller or square rooms.
