Mayhems cooling fluids offers up excellent information on their site regarding their products. The will tell you the life time expectancy, and even warn you against everyday use in their Aurora product line. But they do make fluids that are good for everyday use. But as with any preblended product, you must take precautions. Only use premium or approved tubing, and DO NOT add anything else to your fluids. Premixes come with biocide and corrosion inhibitor already added. Adding inhibitors like copper sulphite WILL cause the dyes to come out of solution and potentially cause clogging issues.
People use premixes ALL THE TIME, and you only here about the horror stories. On my first loop, I had people on the forums go absolutely ape-sh&* over my choice to use a pre-mix, and not pure distilled water. But, I am running absolutely fine after 2 years and absolutely no maintenance. But I used pure distilled water and flushed all my components VERY well, to ensure everything was clean, and there were no coatings or additives left from manufacturing.