The goal of being in a FFL is to win, right?
Why give up one of your elite QBs to someone else who will benefit immensely from it? Yes, LT and Brown are valuable at their respective positions, but giving up Warner would give the other team a HUGE boost in TDs and could cost you down the road.
What happens if Brooks gets injured? If you make this trade, then you would have to scramble for a backup QB, which won't be nearly as valuable as Warner. This is especially important in a TD-only league. Better to keep both QBs and play the hot hand, and use the best QB during each week.
My philosophy on trades is that if someone offers a trade to you, you are in a position of power. No way should you ever accept a trade, unless it clearly benefits you. Carefully consider all the pros and cons of the trade. If you really want to make the trade, always counteroffer first!
Just today someone offered Thomas Jones to me for Qadry Ismail. Now, I had Jones and dropped him a few weeks ago, since he was a backup for me. Ismail is usually a starter for me, unless he has a terrible matchup or a bye. Also, Jones has a bye the same week that I play the other team who offered the trade. Which was one of the reasons why I dropped him in the first place. Oh, and my two starting RBs have byes on the same week! So, I'd have three RBs that have byes on the same week that I play the team who'd have my starting WR. I don't think it would be prudent of me to accept that. I didn't even make a counteroffer, because the other team doesn't have anyone that I'd consider.
Hang on to Warner unless you want to lose!