I went back to Mal'Ganis since my guild of old friends had some logistical issues getting more than one 10 man going. This group is doing 25s, and they didn't start until after the holidays, and had trouble getting rosters filled until about mid-january. I came to them in February (after one of their officers offered me a spot back) and said "a bunch of stuff just happened (they merged with another raid group), give us some time to sort that out". So, I gave them a month and transferred after talking to them again. My Tank gear was full heroic level with some epics (347 ilvl basically), but my DPS gear was much lower than that, somewhere in the realm of 330 or something. Anyway, after a week of sitting out, and a couple weeks of farming, swapping gear, I basically became their break tank on Heroic Chimaeron, their kiter on Heroic Magmaw (and soon to be conclave), and doing pretty well DPS wise, despite having a spec that's currently slightly inferior (about 1.5-2K DPS short).
Since I've started, we had one off week of no progression, then we've killed one new boss every week with the exception of 2 weeks ago for Omnotron. We're now 6/13 and likely hitting 7/13 this week. Not too bad for a 9 hour/week raid schedule and the difficulties they've had before I got there (and after I got there, we had a few people quit, replaced them with some really bad ones - like a 7700 DPS warlock - who were then replaced by some really good players.
So far, being casual has been a fairly good success. I'll remain here until I move across the country. At that point, who knows what's going to happen. We're hoping we can clear the rest of the tier before Firelands, and the longer they delay the patch (and we keep progressing), the likelihood of that happening increases. I've been fighting off the itch to go back to Aftermath, which cut it's raid hours to 13 hours/week, and is 10 (or 11?) out of 13, but I need the time to work on career things at home.