In terms of global access to BBC domestic stations, the big loss is lower bandwidth AAC+ which works great on mobiles via the right apps.
Apparently the World Service is not currently streamed via this infrastructure, but if cost savings are the big motivator I'd watch this one closely.
According to VLC, this is MPEG AAC Audio (mp4a) with AAC Extension: SBR - it is coming in ~65 kb/s.
My take is that for the broadest access you want low bandwidth options for news radio in particular and AAC+ gives you the best quality at lower bit rates.