The new LFR system they are putting in for 4.3 should take care of many of these issues. I've always run multiple toons in 25 man PuG raids and have done just fine with them. No one ever notices that I'm playing 2-3 toons because my DPS is on par and I play different classes.

With LFR I plan on continuing this, but can also do it with other guildies in the raid easily and whenever we feel like raiding. I have 40 toons that are ilvl 368 or so, so I should be able to raid as many times as I want to every week.

In the past I ran some ICC10 solo before they gave us the buffs and of course Naxx and the Winterspring bosses when they were current. After the nerfs to BWD and BoT I can get a couple bosses down solo as well. However, with all the crazy mechanics they have been putting in lately, I'm not banking on being able to solo raids when they are current any more. That probably won't stop me from trying tho ;-)