Well, I just gotta say that I frequently do the 'GGA' or 'nice shot' thing (both to enemies and allies), and I've seen it fairly frequently on the servers that I play, too.

I -occasionally- get sniped or sprayed while typing a compliment or a short 'assault plan', because you can't always wait 'til your dead or 'til map change to say something.. But I think the trade-off is worth it.

The more you communicate, the better the playing experience in the LONG run.