Fentanyl is 100xs more potent than morphine so once you gain a tolerance to 30mg morph, you'll be able to safely do .3mg of Fent-woohoo! Freebasing is just as dangerous as IV because of the massive amounts blood vessels in your lungs. Also, humans only have so many opiate receptors. A nontolerant person would get just as high from an 80mg oxy. The only difference is that Fentanyl would get you closer to falling out/ODing.