I think the Arrow was an excellent airplane, and unfortunately the reason it was not viable was that for Canada alone to operate it would be too costly for the Canadian government to bear. The pressure was on to sell it overseas, and unfortunately US firms with deeper pockets, including having a government with much deeper pockets than Canada's and willing to go to bat for US firms being preferred overseas, is what shut Avro Canada out of the running. And to be fair, one of Arrow's advantages was indeed the Iroquois engine, which was pretty advanced and therefore hard to fix in squadrons way over in Europe or Asia, far from the Orenda plant. Precisely because it was a superior engine, using high-temperature alloys that were much harder than previous generation compressor/turbine alloys, front-line mechanics could not fix them on site. The same would be true of any engine giving the same performance of course! But this is where the political advantage of companies based in a larger superpower, or competing designs made in Europe, especially French ones with Dassault's aggressive marketing again backed by a government that threw more weight around than Canada's did comes into play. For AC to sell it the company would have to be both willing and able to play the kind of hard ball Lockheed did with marketing the F-104--which in fact came down to criminal bribery. I don't know if partisans of Avro Canada want to suggest their admired company could get just as dirty as Lockheed did--at least they'd be stealing the sale of a superior airplane! But Lockheed could do what it did because its prime customer was the US Government with a vastly bigger procurement budget, and that same government was also a very influential lobbyist. AC just could not play that game and win; if merit did not sell the aircraft versus such considerations, they were sunk. And it remains my impression that without foreign sales, Canada alone could not reasonably afford to finance the Arrow for its own air force alone. So it was cancelled.
The idea that Orenda might manage to market the Iroquois engine independent of the Arrow is a little hopeful but I've already given the argument, whether it is overall well founded or specious, that would be put forward that the Orenda plant would be too distant and too small to keep up with repair orders, and that given the superior high-tech alloy composition only made to order repair parts would do, no front-line kludges would work. So again, the little vendor in the little country can make a superior product all right, but can't market it against the interests of big vendors based in big countries.