IV Adderall, in both XR and IR formulations is really shitty man. If you're looking for a rush like crystal methamphetamine or cocaine provide, you're looking at the wrong drug. Injecting Adderall is gross. Basically, the rush is non-existent, you just feel it hit you immediately and peak, and then after about 15-20 minutes (IME), all the 'positive effects' wear off, and you're left feeling overly physically stimulated and paranoid.
Also, unless you're using micron filters, do not even think about shooting this stuff up. The amount of binders and crap in these pills is disgusting, even if you're using the 30mg IR tablets, sucking up that gunk is going to be awfully hard, and when you look at the sludge that ends up in your syringe after cotton filtering the Adderall, you'll probably want to vomit (its fucking nasty). So if you are going to shoot any formula of Adderall, micron filters are a fucking must.
Also, just a warning against slamming the XR beads. When I was young, and dumb (like, 4 years ago lol), and couldn't even spell harm reduction as I was so stimmed out, I did use to do this crap. I'd crush up the beads from 4 20mg capsules (I believe) of the XR pills, and spend an hour or more trying to suck up all the gunk floating around in the spoon. I remember shooting it, and my heart started to beat super fast and erratically. Not in the 'scary but kind of fun' way that cocaine hits you, this shit felt dirty. seconds later I was clutching my chest on the bathroom floor, flipping out, wanting to scream for help but I couldn't because I felt like someone had shoved a sock down my throat. I also had this feeling in my chest as though something gross was filling up my lungs. Not a pleasant experience. A few weeks later I went into an inpatient and stayed more or less clean for about a year, but for about a month I had this huge swollen formation the size of a golf ball rising up from the crook of my arm where I had done this shot. It did go away, but to this day, that vein (where I clearly did miss some of my shot) does not work, and there's what feels like a cyst right under neath the flesh.
Just don't IV Adderall, its such a waste of a good drug. Plugging it is great, it's what I do, and I'd take it rectally ANY day over intravenously. I even had the chance to shoot some micron filtered Adderall the other day, but I said fuck it, and put it up my ass.
As for SC and IM injections, I've only found a few reports of people doing it, and from those accounts it has no benifit over plugging, oral, or insufflation. I imagine that if you had a pure solution of liquid Adderall, or finely micron filtered it may be okay, but I wouldn't go based on my word.