I've been putting together an AONE4 itinerary using Oneworld's online booking tool. It starts in NYC with MEL as the first stopover.

The obvious first flight segments are QF108 to LAX connecting to QF94 to MEL. When I price up the itinerary it prints out with a nice QF letterhead, indicating, I assume, the booking would be made with Qantas?

The identical itinerary, with the same first two flights but input under their AA codeshare numbers, produces...a printout with a slightly less elegant AA header and, more importantly, a price tag some $1,539 lower!

Now I am aware some people have had trouble booking flights as codeshares. And people who have reserved with AA have had trouble with QF and vice versa.

Nevertheless, unless the online tool spits out the booking at the last leg, I am minded to grab the $1,539 saving (which I assume is due to AA's greater generosity concerning fuel surcharges etc.). Can anyone advise whether it would be inadvisable to do so for any reason? Does it affect ease of securing seating allocations or anything similar? Presumably if I needed to make any changes I would have to deal with the (in my experience very helpful) AA RTW desk. Will they object to this, given that apart from the codeshares and a couple of internal flights, none of the itinerary has any connection with AA?

Any thoughts/comments/advice gratefully received!