I worked for a company about 7 years ago that had the stock bagging unit on one of their dixies for fall cleanup.
The idea was to make a few mulching passes and then use the vac to pick up the remnants.
It worked very well when the leaves were dry, but wet at all and you would get clogs. Ultimately you get that with just about any bagger unit though.
Now, I will say that Dixie has changed their bagging unit design since then, so I don't know if there were any improvements made or not.
Over-all I gave it about an 8 out of 10 on performance.
EDIT: just went to the DIXIE site and noticed that I didn't see the unit that was used before. Originally it was a triangular, 1 yard stainless steel hopper with a lever release. Not the bag style that is on the web-site.