One note for you about LFR - if people get realize that you are a multiboxer, some of them will start to get pissy and may start a campaign to kick your toons. Having said that, I've been absolutely amazed at how few times anyone has said anything about my guys in LFR, and if I'm going in, I'm typically brining 6-8 guys at once.

I think the key is having a decent knowledge of the fights (I started with only 3-4 at once until I figured them out), but mainly that I have completely unique names for all my characters. Having lots of very similar names is a dead give away that you are boxing and the uninitiated will think that if you are boxing, you have to suck.

All that is to say that if you are starting in on a mixed team (which I think is a lot more fun) and have the ability to have completely different names, I would highly recommend it.