I think the 749 is an amazing machine, and would love one for mowing my yard. I've had Simplicity garden tractors with both the rear bagger (currently) and a cart similar to the 519 system. I ended up pulling a lot of grass clippings, and leaves from my cart, but it didn't dump as steeply as the 519 does. One member (at least) here has added hydraulic dump to his 519, and can actually use it to push the piles of leaves, etc. back as he dumps. I also sometimes use grass clippings for mulch in my gardens, and for that, the bagger works better since you can carry the mulch where you want, and dump it in a more controlled manner. For fall leaves, I preferred the cart, but for mowing I prefer the bagger. Both have their uses, and advantages.
On another note, I keep hearing about the 2305, and stability. I can't for the life of me figure out why the 2305 (without loader) would be less stable than either the X7xx series, or the 2x20 series. It is the same width, has two more inches of wheelbase than the x7xx, and is heavier??
Is the center of gravity that much higher??