Any time someone makes a statement that you can simply swap primers without any regard for pressures or consequences, I always ask for the data they based that statement on. In loads producing around 8000 PSI or less, you might get away with swapping any primer. With loads in the 10,000 PSI range, you'd be a fool. Tom Armbrust posted an article (link above) about primers and patterns, with a good comparison of a number of primers. The most important thing to take away from the article is that primer substitutions are NOT PREDICTABLE. His warning is simple.....Don't do it! The RIO G600 is sometimes a mystery, but the limited data I have seen puts it in the same category as the Federal 209A and CCI 209M. It appears to produce some rather high pressures. It's intent was for use in large capacity straight walled hulls with single based powders that tend to be hard to ignite. Other "bargain" primers are an unknown, since very little data is published, if any.
The CCI Primers that were discontinued were the CCI 209SC and the CCI 209 T&S, earlier on. CCI currently manufactures two shotshell primers for retail sales. They are the standard 209 and the 209M, which is intended for use with magnum loads. Federal discontinued the 209 and replaced it with the hotter 209A. All notations and warnings I have seen advise against using data for other primers, except for the Nobel Sport, which Hodgdon says THEIR data for the Winchester 209 would be compatible.
Some people have made statements like "I fired a couple of boxes and everything worked OK" or "They seem good to me!". That's a dumb thing to do, since most damage is done over a period of time by shooting over pressure loads on a regular basis. According to HP White Labs, the accumulated stresses on a firearm can cause fatigue over time and result in an eventual catastrophic failure. How many thousands of your "pet" loads would it take to destroy a gun? When will it fail? Maybe the shell you fired when it blew up was not the one that caused the failure. Could it have been the ten thousand high pressure loads you fired in it last year when you swapped some components since you couldn't get what was listed in the data, or got a real deal on some primers?
I like my firearms, my well being, and fellow shooters. I refuse to put them at risk by doing stupid things and perpetuating BAD advice.