I know it sounds counterintuitive, but if you'll put just an 8 or 10 pound piece of flouro on the end of it you won't give up all that much in breakoffs but you'll wear their asses out faster. If you're talking 30 pound fish, you need to scale that up a ways to maybe 14-16 poind test, but I'd definitely give it a try. It makes a huge difference, at least to me it does.
That said, I've not fished for trout that big so maybe there's other reasons you don't use a shock leader.
BKB