Note that you can take heroin orally! It's usually about 6-8 times less potent that IV, typically, ~3-4 times less potent than snorting. Also, it absorbs unreliably -- so what's not enough to get you very high one day, might be too much for you another.
E, meth, etc work great orally, you get like 80% of the substance.... you're only getting 15% with H, it's sorta silly.
-Zorn