Wirelessly posted (BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
Bear in mind that there are no RTW oneworld awards. All oneworld awards are distance-based, and have different rules than a paid RTW oneworld ticket. There is an excellent sticky in the AA forum about using AAdvantage miles for oneworld awards; BA's oneworld award rules may differ -- their redemption rates in premium classes certainly do. And there are likely to be substantial fuel surcharges on the BA redemption. But since BA permits en-route stopovers on its regular one-way redemptions, a oneworld award might or might not be cheaper than stringing together a few one-way awards when using BA miles.
If you have a particular itinerary in mind, why not post it for comment and suggestions as to the most efficient use of miles?