If you don't want to have experience by ear (which you may consider as speculation) than I am afraid you have to join the Line6 developers team to get answers to your questions
Clearly speaking: Line 6 does not give that type of details you are asking for in my opinion. (May be some of the Line6 Experts which have participated as beta testers can answer your detailed questions)
But I can confirm that my ears (speculator
) tell me, that L6 is using cab/sims in their standalone mode and in the 4 original voicings. This is more or less confirmed by the fact of the latest DT-firmware release which gives everybody a more detailed view how a DTXX is designed. So if you want to go for the 4 Voicing to make them sound the same over the POD HD, you should go for standard cab/sims ON when using Line6 combos and cabs.
If you use the DT-amp HEAD and a none-L6 cab, then the story might be different:
Assuming you have a 4x12 cab, I would start with cab/sim OFF on all amps where a half stack is the standard rig, because your own one should do it better than a cab/sim. But if you want to use the BF Double (= Fender Twin) on the same 4x12 cab, I would start with the standard cab/sim ON with the BF double amp model. As you are using a different (none- L66) cab, you have to experiment at that point a bit, because your speakers (which I don't know) are likely different to the Line6 speakers used in their cabs.
Hope my comments still helps, although they are based on speculation respectively experience on learning by doing ...
Gear: JTV 59, JTV 69, JTV 89F, Godin Progression, Godin Seagull, Gibson Les Paul Deluxe, POD/HD500, DT50/212, DT50/Head, Marshall JVMC212, RIVERA Rockcrusher, Radial JDX Reactor
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