I'm all out now, unfortunately, hence why I'm on the AH stuff, but usually I take two ounces a day, I developed an iron stomach, normally it takes me four loaded teaspoonfulls in the morning just to feel good(as in not in WD), then I build from there. With some weaker strains I do up to 70 grams a day, normally I order a kilo and a half from two different vendors each month and have done so for years.
I need at least 20 grams to feel properly opiated, the only proper opiates I can compare with are oxy, hydrocodone, oral morphine, o-dt, subs, poppy tea(both pod and seeds) and today I can say AH-7921, but for me unless I go above 40/50 mgs of oral oxy, I like the kratom better. It just agrees with me, I completely understand how others might feel it's underwhelming though, especially if you have tried heroin before.
I don't think you'd be able to enjoy it if you'd been on heavy duty opiates for an extended period of time.
The longest I did a proper opiate was a three month oxy habit when working in the US, used to do 40/60 mgs a day on top of kratom, obvously less than I would if taking individually, without the kratom I would drop a whole OC80.
Also with the benzos, I was on daily etizolam for a year and obviously on the kratom for the entire time, they mix wonderfully with beer as well and for a time, after quitting the etiz I couldn't get to enjoy the kratom on its own anymore, luckily after six months in Australia, I was back to enjoying as I should.
My advice before was just trying to play the HR thing, it stands if you're new to the kratom though.