yeah, they're pretty interchangeable....as long as you can get your dopamine going you'll be okay, and there's a lot of drugs that'll do that...
the one I found hard to substitute was coke. And had very definite "withdrawals" from that,mainly in the form of severe panic attacks, dizziness, chest pains, tinnitus, tremoring.....went on for about 6 months, was still using speed (but not daily) and pills at weekends at the time....but even the speed, once it wore off couldn't mask or ward off the coke WD's
I don't think panic attack type withdrawals that stim users, especially coke users, can suffer from can be classed anywhere near WDing from an opiate/opioid addiction.
As I said , pirate for one, if I don't do it for a couple or 3 days, the first night will be dodgy getting to sleep .....zaps or close to zaps; the 2nd night a very definite improvement, and by the 3rd night it's fine, or I've got something else down me.
Speed I had to move myself away from as i couldn't stop it, again, al psychological,but I realised it was taking me over and moved to Turkey, still had mild psychosis for a couple of weeks, but then fine, and only used coke for about a year when I was there, and only a weekendly treat.
The story might be very different with pirate if I was in my 20's, no wife, no child, no mortgage, no job.....but as it is, I have to be responsible(ish) with my stim use.