I agree with the OP on stock exhaust and engine (not intake) sound from the E9x. Sitting at idle it's as quiet as a Lexus (or a 335i). Same goes if you are a spectator (like on tourist rides at the Nürburgring), it just doesn't stand out as it drives by. Even a Golf GTI or R makes more noise as they drive past... It's too muffled.
The F8x seems to have a louder exhaust and provides more theatre, apart from cold start perhaps. It seems like it's more like a performance exhaust stock. And then you can have the M Performance exhaust which sounds awesome in the clips I've seen.
I'm a straigh six guy, so that makes it easier to like the noises the S55 makes. If you're a V8 guy, the S55 will be disappointing because it won't sound like a V8. Kind of if you are a big ZZ Top fan, Coldplay might not provide the same enjoyment
