Yeah. I bought a 9mm cylinder for my 357 Blackhawk and I feel like I'm just fine now.
A much more affordable solution for a multi cartridge revolver. IMO, if the goal is a 9mm revolver, just buy a 9mm revolver. The barrel will not be forced to pull double duty with different bullet diameters, weights, and lengths and the sights will be set for 9mm.
And last I looked, two revolvers is better than one. Yeah, that means buying a second gun and revolvers aren't cheap, but they're a lot cheaper and easier to get than a Medusa.
Not that the Blackhawk 9mm combo isn't a bad choice, just saying.
About the only thing that's left out is .380, but given that .357 is a straight wall case, just like .380, I think if one had a .357 that used moon clips and the clips were modified to work with .380, it'll work and be safe.
People have shot .380 in a 9mm pistol before, but the taper of the 9mm leaves a lot for the .380 case to expand in the chamber, .357's case diameter is only .005" larger than .380 is.
Of course, why would one want to shoot .380 in a .357 is a mystery, but I have a prepper mindset and if all you had for ammo was .380... it beats an empty .357.