I 4 boxxed Flame Leviathan yesterday in a pug, was a lot of fun Just split them into two seperate siege engines, follow works fine. Both got targeted during the fights but all I'd do is turn around, speed boost, shield if he got close, etc. My two gunners were the top DPSers on the boss too! The only thing that dropped tho were 2 melee items and the healer neck

I'm 8/14 in 10 man on my DK as main tank, did it in a pug. To be honest I had a lot more fun playing solo than multiboxing ulduar. I can focus 100% on one char, and imo that helps a lot - we 1-3 shotted every boss in my ulduar10 pug, even though only one person had done any of the bosses previously.