Fireline is a great line as far as braid goes yet it still fails to hold a candle to mono as far abrasion resistance, especially backcountry. Backcountry may be the toughest line arround. I mananged pull a good fish out of heavy, heavy, cover (serious rocks and kelp beds) recently. This line held up spectacularly, not a nick on it. That's just my 2 cents, if my oppinion is even worth that. Everyone has their own line preference and for some reason we all defend our own as the best to the death.
