I have a new X739. I use the powerflow bagger for the grass. I'm not impressed with it for heavy volumes of oak leaves. I am using a Cyclone rake Z-10. It works well if you have the space to maneuver it around and does require a bit of work to empty. What are you looking to do?
GJSnow.
I have had good luck so far with the MC519 cart, holds a decent amount of clippings and dumps easily. With the two point hitch it maneuvers easily in forward and reverse.
I have the MC519 as well. Pretty handy little cart and good capacity. Best part is easy dump. If you are good you can collect, drive, dump and reset without leaving the seat.