Different load densities, case designs and bullet weight combinations will cause very different results. In one scenario 560 or 565 might react just like RL26 and in other scenarios they might react very differently. It's hard to find a direct replacement since the chemistry is not the same. That said, I feel that 560 and 565 yield similar results as RL26 in some applications. Not sure about your cartridge/bullet combo but in some.
FWIW, I use N560 in my 284WIN under a 168 and they're screaming out at 2924'sec. 24" barrel, 8.25x. My barrel does run faster than average but still, that's cooking for a 284. Bolt lift is easy and primers look perfect. Accuracy is excellent. 565 in my last 6.5 PRC was awesome. Not as fast as RL26 but close. Cleaned easily and was very accurate. 540 has been one of the best powders for my 308s with longer barrels like 26 and longer. Screaming velocities and very accurate, easy to clean. I feel like 540 is to a 308 as R26 is to a 6.5CM. There's just a near magical result.
I like N500 series powders. Less sharp pressure spikes typically, clean up easily and I get a lot less copper fouling. They're not as temp stable as H powders but better than others. Top end velocities is another bonus. They're not perfect. Then again, there's no such thing.
YMMV,
M
