I haven't gotten a text while listening to Google Music for awhile, but iirc, it's just a small maybe 1 second pause. Unless you're having a conversation while listening to it, it shouldn't be too annoying.
I would think one way to rid of the pause is turning off the notifications in the texting app, though I would think you'd have to do that everytime
Hmm guess turning off notifications won't do anything then. Slight annoyance, but I don't text, or try not to while I'm driving. Unless I'm meeting up with friends or family in places we've never been to. Normally I have 2 other mp3 players for music so my Nexus is usually a last resort source.I think it still gives a slight pause. I have notifications off for gmail, and it still pauses my music whenever one comes in. It is just for a brief second, but it's noticeable. Not sure about mms, think it does about the same, though I have sounds set for my incoming text.
But yeah, if you were constantly being bombarded it would be annoying. Just don't know of any way to fix it.