I've got a 2011 FX4 Supercab 5.0L but I haven't towed with it yet.

I think the article Tim was talking about is this one. This should give you the information you need about how well the 5.0L tows.

Road Test Review: 2011 Ford F-150 XLT 5.0-liter V-8 - PickupTrucks.com News
(Pretty impressive considering that was right at the trucks max tow rating)

I know that even though I haven't towed with it yet I love this new 5.0L!