I really like your posts. You choose a great focus for this GR!

I do think you misread Darcy writing that

"But whatever may be the sentiments which Mr. Wickham has created, a suspicion of their nature shall not prevent me from unfolding his real character -- it adds even another motive."

I read it to mean, 'if Wickham involved you in any serious emotion, it is best for you that it be broken as soon as possible.' In other words, it is a reference to the harm an unprincipled man can do to a young lady's heart if she does not know his wicked nature. I do not think your reading holds water, since Darcy starts the letter saying that he is going to forget as soon as possible his offers of the prior night.

I would also not say that Georgianna's admitting to the elopement plan was necessarily a mark of honesty in general. She may well BE honest, but Darcy clearly says this is a mark of her deference and respect for an older sibling. She was willing to live through the deceptions an elopement would entail prior to seeing Darcy in person, and then changed her mind.

I had not before noticed the parallel with Wickham's declaration of respect for the elder Mr. Darcy, and THIS Mr. Darcy's avoidance of public exposure. Thanks for that!

I do not think you can give Elizabeth less credit than Darcy in changing his opinion when offered contrary evidence: Darcy is bowing to the opinion of a lady whom he has long admired, in part for her intelligence. He also, if you recall, forgave her sooner than she forgave him after their dance at Netherfield

'for in Darcy's breast there was a tolerable powerful feeling towards her, which soon procured her pardon, and directed all his anger against another.'