Even on Twins and imp VE i'm not threat capped... you just need to ensure the 2nd tank gets an early 10K lead before dps. If that doesn't work you need to get your tanks working on threat generation imo.
Another trick is to have your shammy drop TA for the first 30seconds of the encounter and switch to WoA, I know our locks need to but I've found it doesn't really matter for me.