That would be very nice, but even more so offline as when I use OS it tends to be in poor signal areas. The thing is, Bing license the maps from the OS and probably pay a hefty fee, as well as having to restrict their use. I did try and see if it was possible to download the tiles offline, but I messed up the url and got ve tiles. I might try again at some point, but am not optimistic. As for online, can't help there, unfortunately, but watching Bing maps when using them, they do have multiple servers that they seem to round-robin access - ecn.t0...ecn.t1....ecn.t2...ecn.t3....ecn.t4...
ecn.t1.tiles.virtualearth.net/tiles/r/<quadindex>.png&g=41&productSet=mmOS