tolerance is something to consider/take into account with an od ctb.
both h and f can feel pleasant and both are used recreationally. with f, ctb is much quicker, and one is usually less aware - kind of a 'lights out' without much warning to one who might be opioid naive. with h, there's more of an onset.
both are pleasant, imo.
but being revived is a very real possibility, and something to weigh the risks of.
personally I don't think I'd feel comfortable choosing such a method if I'd never used intravenously before.
there is, imo, a lot to think about with this.