Well, I went to the horse's mouth and called up Aqua Rite to ask them about their higher recommended CYA levels. After 10 minutes of listening to some vintage elevator music, the rep told me that the chlorine that a SWCG makes is different than the regular chlorine you just add to a pool.

That's why they want a higher CYA---to protect it from sunburn.

Was she just trying to get me to hang up, or does that sound plausible? Hmmm...