The Rio's still crop up fairly frequently. They were very popular in their day as a lightweight vacuum or a second cleaner, mostly because they were so cheap. It was the cheapest vacuum you could buy for many years. The earlier Rio had a bigger brother - the Solo - that was slightly more expensive but bigger and a bit more powerful.
They never came with a powernozzle. They weren't high end enough for one really, although the TOL Solo did come with an air driven Turbobrush.
In the UK, powernozzle's have never been that popular and were only found on the top end cleaners. When I was growing up, of all the people I knew of who had cylinders, none of them had powernozzle's.
The Rio with the storage box was the Rio stowaway. I have a brochure with one of those in. A great idea, although not unique to Goblin - Hitachi did it a few years earlier. The stowaway is probably one of the rarest Rio's, along with the TOL Rio Grande from the first series. The problem with those models is that they were more expensive. The average Goblin customer usually wanted the cheapest option and the TOL models were creeping into the territory of higher end, better performing brands.
I really like Rio's though. They weren't the best cleaners, let down a tad by crappy tools. But they were very lightweight and powerful, with a decent toolkit they could've been fantastic.