Marginally more. You gain a lot in isolating the baseband, namely you remove RTOS dependencies from the OS on the applications processor and simplify the interface for the OS down to something known (Serial, USB) and the communications protocol (like the N900's phonet interface.) It also allows the OS to be fully open and user-replaceable, unlike Symbian which has never (and is still not) been user replaceable. Overall it's an improvement.