Gene, the grates in the FE (4) are 17 x 24, about the same size as the racks in you oven. You can squeeze 2 briskets on a grate if they aren't too big, say under 12#.
I have one rib rack for it that replaces one of the std grates that will hold up to 10 racks of ribs, although it works best if you only put in about 6 or 7, which is still a real space saver.
Heat distribution in the thing is amazing. I often cook large quantities of bacon in the FE to put in the freezer for later use. With each rack totally loaded every piece comes out the same. A lot of FE users claim there is a hotspot in the back left corner of the second rack from the bottom, but I have not experienced that with mine.
The big Traeger runs about $2,000 the FE runs about $3,000 for me that extra money was easily spent for the added capacity and huge advantage of the insulated smokebox. I've never cooked on a Traeger but I have little doubt that I use 1/3 to 1/2 less pellets of the uninsulated Traeger.
One more note, none of the pellet cookers (IMO) make great grills. You can cook a steak on them but they just don't generate the same direct high heat of a gas grill or charcoal fire. I like a lot of heat to sear steaks and chops when grilling and they just don't do that very well.