I dont see how people accidently die from heroin I have seroisly tried twice now (not a cry for help thing). Its bullshit even with benzos in the mix once ur a junky tolerance is such a fucking huge factor.
It's cool if you don't want to answer, but what is your preffered method of use? Injecting? Snorting? Eating? Smoking? You get the picture...
Anyway, I agree that once one has built up a large "junkie" tolerance, as you say, it's not exactly easy to over-dose. But that doesn't mean it can not happen to you....as every now and then you will receive a batch of extremely powerful junk out of the blue and if your dealer/hook/connect does not warn you...well, that is when the sad side of our habit shows its ugly head.
If you're a sniffer/smoker? Yeah, it's not easy to OD, but it can happen, so please be safe and always do a tester sniff/shot/smoke/etc...yeah, it sucks being paranoid, but if you've ever lost a good friend to an OD you'd understand.
If you're playing around with benzos and dope? It's even more important to test your dope and while I know the combo feels good, it's not wise to mix the two, because you will accidentaly cross that line eventuallly. Keep some narcan close-by and ALWAYS have a shot of it(the narcan) ready to go...best of luck friend...enjoy the weekend