A little different view.

I got into a discussion one time with an old timer over this same question. I was concerned about using a lightweight leader so I wouldn't lose my flyline. We were discussing using 30lb test for a leader in rocky big surf conditions where a fish could easily rub through a double 30 lb leader. His response to me was we don't fly fish to save money. If I had any hope of landing a good fish 30 lb of hard mono was the minium leader to use. Everytime you throw your line out there with any type of leader you risk losing it.

First of all try an put 20 lbs of pressure on a fly rod. Unless you are pointing the rod at the target you can't do it without ending up with a multi piece rod, more than the two to four pieces it should be. Fly rods are good at protecting light leaders and delivering presentations. They are poor at hook setting and putting heavy pressure on fish.

I took his advice and haven't regretted it yet. I have had small fish rub through 30 lb hard mono not because I put 30 lbs of pressure on them but because it wore out on the rocks. I have not yet lost a fly line to a snag or a fish. My hooks will usually bend if I get a snag before my leader flyline or backing parts.

If you are really worried about it get some really heavy backing or use a light leader and plan on losing a lot of fish.