As the Royal 501 guy (check my profile), I'd say go for it. They're not all vintage anyway. The contemporary 501s have 1.8 amp motors, Royal lables on the front of the machine, and have a thumb guard in front of the switch. If you want the most power I'd look for one of those. The older ones have 1.2 amp motors with carbon brush caps and oil fill ports. They can all use Royal Type H bags.
The cloth bags were available up until recently. If you get one with the square pattern of "Royal" and crowns, then it should last a while. Those bags seem to be made of heavy material. The belts and brush rolls are the same as the Dirt Devils and are still available. The attachments are also compatible.
The other big advantage is they look so cool.
Shown Below: Contemporary 501, Pro Series, Thin Bag.
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