In a sense, these two products are intended to accomplish the same thing (supplementing alkalinity, calcium and some trace elements), just in different forumlations. Two Little Fishies' "C-Balance" is a two-part calcium and alkalinity supplement with some added strontium and magnesium. One liquid contains sodium carbonate/bicarbonate, and the other contains calcium chloride, strontium (probably chloride) and magnesium chloride and magnesium sulfate.
The Red Sea product is an all-in-one powdered combination of the above. One reason it's a powder is that it's impossible to supply a single liquid with both calcium and alkalinity without a tremendous amount of chelating agents or in an extremely acidic solution, because the calcium and alkalinity would immediately precipitate as insoluble calcium carbonate. Lots of chelating agents or extreme acidity would both be undesirable for a reef tank.
I've never taken a poll, but I suspect the vast majority of us on the chemistry section of Reef Central don't bother with pre-formulated calcium and alkalinity supplements. They tend to be a great deal more expensive than just buying bulk calcium chloride, sodium carbonate/bicarbonate, magnesium chloride and magnesium carbonate and making one's own liquid supplements, and the addition of strontium and other trace elements that have been pre-formulated into a calcium and alkalinity supplement can lead to undesirable accumulations in tank water.
If you'd like to "roll your own", Randy's written several excellent articles on the subject (one of which is
here), and you can conveniently buy the chemicals from Bulk Reef Supply and other sources.