Nah, you get better advice here than from any TA unless they specialize in RTW's (niche market). While you raise valid concerns, they do not apply to the OW xONEx product. Date changes are free, backtracking is permitted within continent, don't have to add up all your mileage, changing the routing is permitted with reasonable fees, and you have a year to do it all. That's why we love the OW product.

MiamiBeach--I keep forgetting about the n/s HKG-JFK, so yes that may be a better choice than HKG-LAX.