Longer time in the secondary vs a more accurate FG?

I'm wondering whether there would be any benefits or detriments for leaving my beer in the secondary carboy longer for flavoring vs bottling it when the FG hits its mark (or at least is very close)?

The beer is a Fat Tire clone (recipe) in case you want to look at the ingredients to see if that will play a part in your answer.

Sure. Many bulk age their beer, though you can always bottle age too. The differences are subtle, but you certainly want to wait at least until the bulk of your yeast falls out of suspension.

For one, "when the FG hits it's mark" is a bad statement. FG estimates are just that - ESTIMATES. If you go by the estimate and blindly bottle when your beer hits that mark, you can end up with bottle bombs. You want the FG to stabilize, regardless of where it stabilizes, (this means, usually, you either primary for 3+ weeks to ensure all fermentation is done, or take 2 readings 3 days apart and make sure they are the same).

Other than that, the longer the beer sits, the better it will usually be. No worries with a long secondary, (or even long primaries....I routinely go 6+ weeks in primary).