Example dialog from my graphic novel. For the record, Dante believes himself to be a flamboyant actor (he's just recalling memories as a persona). [transition to Sagan's approach] CAPTION (BES) "They sent a first staffed mission to one of their outer worlds. Ambitious for their technology, but unorthodox considering they are close approaching their filter event." CAPTION (DANTE) "You introduced yourself before that occurred? Really my dear, all this time, I thought it was a male only thing to be...premature." [more of the Sagan's approach] CAPTION (BES) "Nothing like that at all. It was neither entirely real nor entirely faked. Just a bit of excess. You of all people should know how drama appeals. CAPTION (DANTE) "Thaaaat's the BES I know and loved. Always with a plan and a plan within a plan and a backup plan, just in case. They should name a fragrance in your honor: Sweet Contrivances. Tell me more."
If it's true to the character, then I see no reason why it should be bad form (unless it's children's fiction). If, however, your Dante isn't (or wasn't) flamboyant etc., then it could be misleading to some readers.
This is chapter one of the novel. Dante accepted a cerebral implant that's given him the memories of other people from the past but different worlds. The memories are showing as personas. BES is trying to get them to acquiesce, but I'm using it as a device to bring the reader up to speed as to what happened up to this point. It's also intended to setup what the story is about. So, yeah, this is not Dante's personality, but it was said earlier that it wasn't his personality.
It will be way too subjective to get a "true" answer. But it's used and often, so I personally say go for it.
Depends on your audience. I don't think it's cheap or bad form... Just don't overdo it, but that applies to pretty much everything.
