If your friend is not wanting to risk a dumping event, ever... then why not look at CaRx. I know that they are a different paradigm, but one of the reasons that people like/move to them is that they are reliable and safe, don't dump and cannot crash a tank.
As you have mentioned many times, there are risks with any doser unless you add stuff manually. It is smart of you to look past the short-term reviews and fanboy stuff...well done. If doser is all that is considered, the just pick, have a backup plan and watch like a hawk.