Been on here quite a bit, plus a lot of other reloading forums.
RCModel gives very safe, smart advice.
Burn rate charts are good for comparing ranges. Like VV's burn chart says N165 is pretty close to RL22. So if I get bored of RL22, can't find it, or whatever decide to go with a VV powder, I know N165 is the one.
But I think that is as far as the comparisons go. They may act differently at different temperatures, etc.
H110 and W296, for magnum pistols, are sometimes said they are the exact same powder. But who knows? Were they the same before the acquisition? I think W231 and another Hodgdon powder (HS-6, or HP38) might be the same as well. But I will still use the exact powder from the recipe.
Looking at some load data for my 7mm Mag, the loads were for RL19, RL22, and RL25. They were all about 150-200fps difference and 2-3gr difference. But I wouldn't swap data on even those.