I get where you're coming from with Nomads, but no idea why you singled out Rockerboys.
And Techies will do what they can with what they have. Would you expect a Techie to hook your leaky tap up to the mains to install a new gadget in it? Some Techies may prefer old fashioned technology, less of the electronics and more of the mechanicals.
Sometimes, to leap forward, you just take a step back.
I'd only hire a Street Techie to fix my plumbing if all the normal plumbers died trying to stop the sewage monster crisis of 2056. Thankfully the boys in red & green saved the day.
I think I agree that some Techies might go 'hipster' though, using older technology to try and one-up the newer stuff. Possibly to make a statement I guess. I still think they'd take more pride in their work if that was the case. I sorta like to lump Street Techies with Netrunners in the fact that they express themselves and show off their intelligence through their handiwork.
It's also kinda the reason I lump Rockerboys and Nomads together I guess. Their actions are more driven by passion, emotion, or loyalty to the group. They might be knowledgeable in AV equipment or motorbike repair, but for higher technology, i'd say most of 'em really don't care as much as Street Techies.
When I think Rockerboy or Nomad, I think I see something like this in my head.
I see them as rebels, people who aren't cut out for a desk job or a quiet suburb. Living everyday on the edge and in general just trying to survive. Not that I dislike rockerboys or nomads, but I don't see most of them as knowledgeable enough to know the inter-workings of any really exotic technology (unless they've had a lot of experience with it of course).
When I think Street Techie (or Med Techie), I think I see more of this.
I see them as thinkers, tinkerers, builders, and mad-scientists. They just gotta take apart everything they get their hands on. They may not understand how everything works, but they at least know what it does and how to use it. They've got gadgets, gizmos and tools for every situation they can of.
I don't know if the average street techie could take on a Rockerboy or Nomad in a straight fight. If a street tech was cornered and in a pinch, they'd prolly pull a gadget out of their ass.
I guess what I'm trying to say is, wrapping your rifle in duct tape, paperclips and chewing gum just to keep it held together shouldn't REQUIRE a street-techie. It could be done by anyone.
Integrated robotics, sensors, enhanced firing mechanics, and so on, might require someone more skilled, like a Street-Techie.