A Marshall cab will sound like a Marshall cab. But two Marshall cabs do not sound the same if one has V30s and the other Greenbacks for example. And there is where I think the difference is. The Kemper Cone will make possible to change the sound of your speakers on the fly. I think that is a tall order and doubt they got it 100%. But the idea is genius.
Of course you will not make your Marshall cab sound like a Mesa cab. But neither the FRFR cabs do that.
Sorry dude but I think this is wrong. They have isolated the speaker part of of the profile so you can change that specifically.
Therefore if you run it through a regular cab, its unlikely to be effective. In other words if you have V30's in your 4x12 and you use the cone, with G12's, it will sound like a mix of the 2...there is no way it can make your V30's sound like G12's, mainly because it won;t know what cab you have.
For FRFR the speaker adds less colour and hence should be more accurate.
Therefore this is more applicable for FRFR than a regular cab. For a regular cab you still want to use DI or merged profiles.....however, I might be wrong as I'm just going on the press releases..