Some of us ordered the SM100 scrubber look-a-like during the bulk order conducted by Stevenkoh and myself.
Bro Steven loves his dual, and I barely started mine.
Some users from other forum did complain of scrubber staining the water. However, SM did mention in his thread that it must be clean frequently, else the bottom layer will brown off and die, leeching color to the tank. Make sense to me, but I suppose the color could be remove by Ozone if you are using one or maybe even activated carbon.
If I ever complain, it would be the power consumption. Running more than 100w a day including the 4 x 24w T5 tubes and pump for 16 hrs everyday is not exactly very economical.
The theory behind the use of scrubber is very logical but some members might feel rather extreme either way. You may want to start up one to help the cycling as the scrubber is truly effective in removing spikes from Ammonia, Nitrites and Nitrates. It might not be a holy grail to reefing but definitely able to control any sudden spikes.
If you are DIYing, remember to design one for easy cleaning, and to clean it every 4-5 days.
Hope this helps.