Widening the rear with any method still using the stock axle will increase the chance of bending it due to the extra leverage put on it. Unlikely though, the wheels usually bend before the axle does.
The warrior wheels might give you an inch or two but it won't be the 4 inches that they give on the warrior, the raptor's axle is shorter stock due to the offset of the wheels.
For the money, the G-Force axle seems like the safest route to widening the rear to me. Not only due to the strength and warranty on it, but also because you can sell that stock axle and recoup some of your investment, or keep it and sell the g-force if/when you sell the 350. I guess it depends on how much you ride and how hard you ride, but with spacers or offset wheels you could end up not only bending your wheels and needing new ones, but you could also end up needing a new axle anyways. I bet you could make about an $80 profit on ebay selling the stock one if you clean it up nice, just something to think about, offsets the price so it's almost like getting a new aftermarket axle for $120!