I have had the Fat 2 into 1 on for about 6 years.
I had thought it had the quiet baffle since I ordered it that way from a vender. You can't tell the difference visually until you remove the baffle, which was quite a chore.

I switched to the quiet baffle about a month ago. It has transformed the bike.
The fact that it is quieter and has a deeper/lower sound is what I was after, but it also accelerates a lot more seamlessly although I didn't have any complaints with the power before.
It seems like I am riding a new improved version of my bike.
Tom

 

Depending on your other mods...a little back pressure from a "quieter" baffle will often give you a little more oomph down low. My VH shortshots were just too loud, so I put in the "quiet" baffles. Just quiet enough...and more pull just off of idle. Enjoy.