The set sold at lockpickshop is made by Peterson:
http://www.peterson-international.com/tensiontools.htm
I like the idea, theoretically they should give you more room to work and there may be some feel benefit to having the tool anchored at both the top and the bottom.
Also, some locks seem to have a keyway shape which is hard to get a good grip with just a basic "L" shaped wrench. This style should work well on any shape.
I just ordered a basic SouthOrd set as a gift earlier today and bought myself one of these sets, so once it comes in I'll let you know what I think. In the meantime, I'd love to hear what some of the veterans have to say about this style.