Raf, BF MT's aren't bad in the snow... keep in mind, I think our RWD Astro van handles good in the snow too so your mileage may vary.
Chunky treads clump up with snow and don't clear well.... Mud Kings, Pro Comps, Super Swampers etc.
BFG MT's are a tighter but still agressive tread pattern. True mud runners laugh at the notion of them being mud tires. They should be considered an AT tire.
Don't get me wrong; they're a great tire overall, just not a great 'mud' tire.
I had 29's-33's on my XJ. The best winter tire was the 32x9 BFG AT. The best all around tire was the Goodyear MTR 31" and my 33" BFG MT were too big for the street and too wide for the snow. Tons o fun offroad though!
Siping your 29's will help especially in slushy wet weather but probably negligable difference in snow.
31" Toyo OC AT's going on my Suburban tomorrow to replace the Mich LTX AT's. I hope I don't regret it!
Sometimes wide is good floating your 2' ground clearance on 2 1/2 feet of snow!