I agree that CW would be haunted by eight-year-old memories when staying at Kellynch. However, I think he would also see the bitter irony of staying there--being welcome in a place where he was never welcome before(except by Anne of course!). I can even imagine him feeling a sense of bitter triumph as he was being led to a guest room--along the lines of "Not good enough to stay in your house, Sir Walter...Ha!"

But I don't think that feeling would last beyond the first couple of days, so perhaps he would go to Uppercross more due to his past association with Kellynch than to court the Musgrove girls...on the other hand, he is ready to marry (as he declares to his sister, any woman between 15 and 30, and a few compliments to the navy and he's a lost man), is finding his Uppercross visits entertaining despite Anne's presence (which would remind him of his broken heart even more than her house would), and, if uncomfortable at Kellynch, he could have reverted to his original plan and gone to see his brother the curate. And yet he stays on at Kellynch, and goes to Uppercross daily...I think it is due to the Musgrove girls, at least in CW's conscious mind! Whatever Anne might mean to him is still buried deep down.