We will skip the health hazards of methanol because if people are willing to run meth injection in a separate injection system they aren't concerned with the health hazards anyhow. FYI if you didn't know though, ethanol is what we drink and other than causing you to make poor decisions there's not much bad about ethanol in small quantities. Methanol on the other hand causes permanent blindness with ingesting as little as 1oz. And worse, methanol is absorbed by your skin. So over time you can accumulate 1oz of absorption just by spilling it on your hands.
https://en.wikipedia.org/wiki/Methanol
(Ok, so we didn't skip the health impacts)
But lets talk about how ethanol and methanol affects fuel system components. First off ethanol has no impact to any fuel component in our cars. None. Zero. And as an added piece of mind Continental actually certified the N54 DI injectors e85 compliant.
Methanol on the other hand...is highly corrosive to our fueling system. Most importantly our HPFP and Injectors. Not only does methanol impact most rubber compounds elasticity (i.e. it breaks down most rubbers), it's highly corrosive to aluminum. This is why meth injection systems use viton and other special plastics in the lines, tanks, and pumps. Running methanol of significant quantity through an aluminum pump housing like our HPFP (and most importantly letting it sit there in periods of non-operation) will eat the aluminum. Again, this is why people pay for special methanol pumps.
With the cost of a set of injectors running north of $1200, and an HPFP getting near $500 I would say it is probably not wise to advise people to run meth mixtures in their primary fuel system. It just isn't worth the risks when you can get 90% of the benefits from ethanol directly from the pump in most instances.
If you need meth (for whatever reason), use meth injection. It is designed to mitigate these potential problems.