After reading several threads it seems that most people strain the trub before reaching the fermenter so that you don't lose beer during racking, but would leaving the trub in the fermenter help to add more flavor and aroma to the beer, especially if using flameout additions.
Some will help yeast health. Too much is said to be detrimental for flavors in some beers, like light colored lagers. The Germans are said to have the wort in a settling tank for a day, then rack off the trub and add the yeast. Production breweries will dump the trub from the conicals. Some will centrifuge out of the boil kettle to the fermenters. The correct answer is that it depends.
IMO you don't want a lot of it. I strain my wort, but of course a little bit gets through. Just like it would if racking after a whirlpool.
If you get a lot of cold break, you will affect flavor. It will provide a bitter taste. I will typically brew 5.5-5.75 gallons and to a quick whirlpool so that I can leave behind has much trub as possible, but it is impossible to keep all of it out. You do want approximately 25% of the cold break to get into the fermenter, but at home, most people don't have a way of measuring, so you'll have to eyeball it.
I've heard Chris White say this, but it seemed more of a theoretical point than a practical one. I've yet to come across "too little trub" as the diagnosis of a fermentation flaw. In the rare case that the yeast are undernourished, adding some yeast nutrient to the boil would be more convenient than trying to get more trub into the wort, no?
Chill and allow the trub to settle at the pitch temp, rack the next day to another fermenter. Or I can dump from the bottom port on the conical.
A little goes a long way. Too much can give a soapy flavor IIRC. Fatty acids are what the yeast use, but fat is a soap ingredient. http://www.howtobrew.com/section1/chapter8-2-3.html http://www.byo.com/stories/item/890-how-to-remove-trub
If you're concerned that you aren't getting enough out of your flameout additions then you should let your beer steep at warmer temperatures after the boil (or whirlpool) before completely cooling down to pitching temperatures.
With lagers I sometimes first rack the wort to a bucket with a spigot and let the cold break settle before transferring to the fermenter. Typically it only takes between 30 minutes to an hour for the break material to settle out below the spigot.
