Both have validity and both are easily remedied. It has become much more common in the past 10 years to regularly sanitize resin with a small amount of bleach in the brine tank annually. Chlorine damage is cumulative, annual sanitizing has very little affect on resin, considering the 40,000 - 100,000 gallons of water the average softener sees in a year. A well system that is not chlorinated should definetly be sanitized annually, or softeners on chlorinated supplies that are pre-treated with GAC to remove the chlorine.
Iron... this always starts some weird debate on this site, and it gets tiring going through the same old and tired arguments. Several on this site agree that softeners can treat iron, but with the modern medias available, and simplified equipment, and the innefficiencies of using the softener as an iron filter, alternative treatment methods of removing iron should be considered. A softener that is used for iron removal has to use a compensated hardness, basically an 85:1 ratio, this is not efficient, but it definetly works. Manganese has a 425:1 efficiency ratio when done on a ppm basis. Both of these common water problems are easily treated with some additional costs up front, and some additional equipment. Water softeners that are used for iron removal should be regenerated often, and with higher salt doses as you read in the article. Other methods include chemical drip systems (acidifying the brine solution with phosphoric acid), and regular chemical cleaning of the resin with acids.
It looks like you understand the common sense part of it. Now to throw another idea your way. Channelling is not an issue in most properly designed resin based systems for a simple reason, the media is round. Irregular medias like GAC, filox, filter-ag, calcite, mag-ox etc should be backwashed more regularly due to the shape of the media. That is why many resin based systems that are single use do not have a backwash valve and they are downflow. Irregular shaped medias tend to be upflow if they are not going to have a valve due to media compaction, and the potential for channelling. Consider the rack of balls at wal-mart, once they settle, they can settle no more, and the can never block water flow. Unless the balls pop (the crosslink structure of the resin fails and the medias fracture) The main requirement for this design is that sedimnet be removed prior to the resin. DI tanks, Arsenic removal resin, post RO polishing softener tanks, etc all designed for single use, and are designed to last for several years do not require backwashing.