This may not be quite the right forum, but I know the site demi-gods will move this thread if needed. Basically, I'm curious why you would use a buff frame addon if your unit frames can display them. Personal taste? Performance, easier to config etc... The one thing that comes to mind is the unit frames could get crowded if you have a lot of buffs/debuffs.
I'm not trying to start a flame war or promote one addon over another. This is just something I've been curious about for a while.
"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff, The Tao of Pooh
I have buffs displayed top-right by one addon, while debuffs I have on my player frame, handled by oUF.
Then anything that is critical to my rotation is pretty much in the middle of my screen, handled by a third addon (typically WeakAuras). This does mean I have (at times) the same buffs displayed in two places.
The main reason why the buffs are handled by a separate addon than just a pseudo-unitframe from oUF is because oUF doesn't handle cancelling buffs.