^ Hm... that's a very wary one to be. If your mix doesn't need it then it doesn't, just don't do it and sacrifice sonic quality for the sake of loudness. I honestly don't give a shit about how loud my mixes get.
What this man says. A hign rms via means of genocide of dynamics does very little compared to what a presence boost can achieve. Excessive amounts of bass can also eat up headroom and give us rms values crossing -7db. All we're then left with is a muddy, squashed mix with no life. Mixes like that also have the tendency of clipping the crossovers of consumer-grade speakers.
To some it all up, for loudness you need a balanced mix. Not necessarily a mix that's nice to listen to, but balanced.