My lawn tractor bagger had a hard time not clogging while picking up fall leaves that were the slightest bit damp, which is common in Western, PA were it always rains. Also, twigs were sometimes would get caught in the bagger shoot. Keep in mind though I was using a 14 year old tractor and bagger system. They new ones maybe better. But I would think a sweeper would be better for leaves and twigs.
This is a great debate, and I'm very curious to hear other's replies
I bought the double bagger with my DYT4000. Never have a problem picking up most anything. My Dad had a rear sweeper for his Cub Cadet, had to weight it down to pick up leaves and such. Finally gave in after trying my bagger and bought one for his Cub. That's just our experience, but thought I would toss my 2 cents in.
I've used my twin bagger for over 5 years picking up maple leaves, wet and dry, pine cones, pines needles and who knows what else from my yard and driveway. It rarely clogs, and is very ease to clean if it ever does. I can also maneuver easily around the property. The "Bags" are actually thick molded plastic and have held up very well.
The advantage of the sweeper over the bagger is picking up things you don't want under your mower deck, and dumping is a breeze, just back up to where you want it and pull the rope. Mine regularly picks up the kids toys, large sticks, horse/dog poop, rocks and many other non grass objects. The disadvantages of the sweeper other than real bumpy ground, is if it's set too low it will beat-up the grass, also the rear plate on some mowers is too thin and will bend with a full load.