There's instructions but they're in Chinglish, they do say that you should use IMR's.
I assume that if you've gone to the trouble of buying a mod on the basis it has a variable wattage feature, buying the additional end cap,etc then you're not the sort of person that would allow your batteries to drain that low.
If there's a risk, it's tenuous at the very best.
The original post from CV9 doesn't really go into her testing methods, sounds almost like a warning based on speculation.
There's obviously something on the board that checks for voltage and adjusts the output to buck or boost, I'd imagine if it detects 4.1 volts or lower it'll switch to boost for the 18650. Even if it switches to boost beyond that voltage, i.e.- 4.6 volts, it would still mean that your 18350's would have to be drained to 2.3 volts in order to fool the device.
If you're only using your 18350's in the Zmax or Vmax, the unit stops "bucking" at 6.2 volts so your batteries wouldn't drop that low anyway.