Flakes will make it tougher to find smaller parts, but they do have a few benefits...
The cover a host of sins. If you have an older floor, or even a newer one, that has a lot of pock marts, divots, cracks etc that you don't want to repair beforehand, then a good coat of flakes will hide those imperfections nicely.
Likewise any marks you may get after you install your floor will be less noticeable.
A monochromatic floor will show dirt and dust pretty easy, so if you're the Felix Unger type you'll find yourself weeping and cleaning frequently. Adding some flake will allow you to be an Oscar and hold a brew instead of a broom as you watch the game on your bigscreen.
To mitigate slip & fall potential a lot of jobs add a grit additive to the coating, these can be pretty visible on a monochromatic system whereas the grit will be camouflaged.
There is no "right" amount of flakes to use - if you want to see what the different coverage rates look like, check out
this post:
http://www.wolverinecoatings.com/forums/index.php?showtopic=1012
Personally for a "light" look I figure about 1 pound for 100 ft2. For full coverage it's 0.15 pounds per square foot, or 15 pounds per 100 square feet. For medium I figure 0.07 lbs per square foot. Personally I'll go anywhere between 0.01 - 0.07/ft2, but more than that I go right to a full broadcast at 0.15.