I agree with Kenny on this one - I'll try to get a picture on our MX5800 carrying a 2000 lb plus skid of wood bricks around. I sure it would handle 1200 lb bales no problem at all.
I'm sure it will, I imagine all the MX series will but...
It all comes down to CG and terrain. The actual lift capacity has little to do with stability and uneven terrain when moving (transporting round bales on a spear attached to a loader frame). Even with my M units, I always keep the bales close to the ground when moving across a hayfield and I position myself at 90 degrees to the trailer bed when loading bales with the bale as close as possible to the trailer before lofting the bale to load it. That really applies when loading the second tier because the CG is much higher and stability is compromised then.
I have 2 method's of loading my bales and it depends on what equipment I have available. I have a 2 pin quick attach bale spear I use on the 105 and I also use a bucket spear on the M9. The bucket spear has a fixing bolt that goes through the bucket floor that secures the spear to the bucket itself but because the spear is far from the pivot point of the loader frame it's more unstable that the 2 pin spear.
Just depends on what tractor I'm using at the time.
U would suggest that with the smaller MX units to use a spear that is close to the pivot point on the loader. That gives you more stability when moving and a greater mechanical advantage when lifting bales.
All distills down to your pucker factor, the terrain and how high you lift a bale to set it, whether it's on a trailer or in the barn for storage.
Years ago I quit storing rounds on their sides in the barn because the go from round to oval and when selling rounds, an oval bale isn't asthetically pleasing so I store my bales in the barn stacked on end, 3 bales high with the bottom bale on a pallet to keep it off the floor and dry.
To do that, I set the bales off the trailer and flip them upright using my pallet forks and then using the pallet forks again, stack the bales in the barn for storage. They keep much better than way,especially when selling them as buyers want a 'round' bale, not a sguished oval one.