Leaving beer in the fermenter Vs. bottling.

So I have a DIPA from Northern Brewer in my fermenter. They say it will be "ready in 8 weeks." So the question is, what is the difference between leaving beer in the fermenter for 6 weeks, or bottling at 3 weeks, and letting the bottles hang out for a month or 2? As long as the FG is on target is there a reason to leave this in the fermenter any longer?

Bulk aging on the primary yeast cake for a few extra weeks is a great way to clean up any off-flavors created by the yeast. I'm not sure I would leave it in the fermenter for 6 weeks, but 3-4 would be great for the beer. If you bottle now, the yeast will go right to work carbonating and forget about the off-flavors for awhile.

I'd leave it in primary for 3-4 weeks, the bottle and allow it to sit until the 6 weeks is up.

There is a lot more than happens to the beer after fermentation is done. Your beer will continue to clear and condition after fermentation is done. If this is done in your carboy, you can leave behind the byproducts in the carboy, but if you bottle, you may have leftovers in your bottle when you open it. I prefer to condition in the carboy and let the beer clear, then keg or bottle.

I just realized this is a IIPA though and I am guessing you are going to dry hop it right? If that is the case, I would do something like 4 weeks in primary, 2 week dry hop and then bottle.

I did dry hop at 2 weeks. It has now been 3 weeks total.

I think it was early for the dry hop and would leave it alone for another couple weeks, but it will be awesome either way.

If your beer has reached it's final gravity, I would say let the dry hop schedule determine when you bottle. Some people say that dry hopping for longer than 2 weeks isn't good (do a search and check out some of the posts). If it were me, and the FG was reached at this point, I would taste the beer in another week. If I liked the dry hop profile, then I would bottle.

+1 on the above advice. I don't suggest dry hopping for more than 7-10 days unless you plan on doing multiple hop additions. So, if you added 2oz now and then removed them in 10 days and added 2oz more, then you'd be fine. I've never tried that, so don't quote me on it, but the reason I don't leave my hops in the fermenter more than 10 days is because of the grassy/veggy-like flavor you'll get.