The only drawback with that method is that you don't get a high enough pressure at the injector to acheive proper atomisation of the stuff being injected.
Water/meth injection works the best when the droplets are the finest possible mist. The more surface area the droplets have, the more heat they draw from the charge. (And the better they can do it)
This is why when the fire service are fighting a fire inside a say a house, they'll set the branch to spray a fine mist into the air. (Albeit at great pressure, and fed from a 90mm hose) This has the best impact on drawing out the heat, and cooling things down.
Likewise, if you run a higher pressure to your injector, you get a better mist. I quizzed out a mate who does irrigation systems. He said all the nozzles they use need high pressures to get a nice mist. When the pressure is too low, they just dribble.

The eaton blowers are a far btter unit that the toyota ones, but their size and shape makes them an awkward install on a datto. Plus the jury is out on if the coatings on the rotors can stand having fuel passing over them or not. (I have an M62 here where the coating is begining to delamitnate.

And on the blower oil thing, I found some for sale on trademe years back. Well well below what it costs full retail. It has a unique silicon-esque aroma to it. Not like RTV silicon, but more rubbery.