Thanks for posting that article, Dana Riddle is an excellent source. It's good to see hard numbers and it's a shame that manufacturers won't spend the resources to achieve this themselves.
As I stated before, Vortechs work around most of the potential problems that arise from powerhead applications. I still argue that they have the following drawbacks...
1) Only suitable to be located at opposing ends of the tank. They cannot be located on the front, or easily on the back, or on the bottom, or within the reef structure, as closed loops can.
2) They are not directional, meaning they are limited to pointing forward (not up or down or at any other angle).
3) They cannot be easily disguised inside or outside of the tank.
4) They require a network of wires running around the outside of the tank.
5) They are slightly louder than a closed loop pump. CL pumps can be remote, while Vortechs must be on the side of the tank.
6) They give off more heat transfer directly to the tank wall (some acrylic tanks have had stress crack issues. According to Riddle, the external temperature is 138F.
7) They cause vibration within the tank which can disturb livestock.
8) Circular or laminar flow is not possible with Vortechs. Water travels in one direction from end to end hitting the opposing wall or opposing flow. I read the velocity numbers, but I don't have pressure pump values to compare them with.
9) I don't know how often Vortechs need to be serviced, but CL pumps have at least 10 years before the volute needs to be looked at. Calcification only occurs on metallic pumps, so magnet coupled pressure pumps don't need to be soaked in acid. Vortechs have not been on the market long enough to establish longevity.
10) There's always a #10. Vortechs are hard to use with tanks that have cabinetry that covers end walls or aquariums fit into walls where access is limited.
The extra 100 watts used by a closed loop pump (if that is truly the case) would not be 100% heat generation, and even if it was, it wouldn't impact the cooling system of a house. These days most people open windows before they turn on the A/C. I'm not about to argue that it contributes to heating your home in winter either
In my opinion, the flow from a closed loop pump has more flexibility to be used for better flow dynamics than a Vortech system. By no means does this make a closed loop system a license to use poor flow placement, nor does it exclude Vortechs from fulfilling some of the flow requirements of a tank.
If optimum flow dynamics are in place, which is more readily achievable with a closed loop system, a 15x turnover ratio can be just as effective as a 40x turnover ratio. It is arguable, that 3600 GPH with a closed loop is worth 4800 GPH from a well configured Vortech system.
If you aren't particular about aesthetics or flow dynamics, then Vortechs will work well for you. If you feel you can recoup the initial cost of a series of Vortechs with energy savings, then it has further added value.