I don't own one, but I researched them (Trac Vac) a few years ago in anticipation of purchase. I didn't as I learned that it is good for the soil to mulch them. What was your question? If I can answer competently, I will.

Here's a link for one, various manufacturer's out there. essentially, you coolect/chop leaves, etc. then it goes through the tongue mounted mower/shredder/vac and deposits in the integral trailer. I've seen them work, pretty neat if you can justify the $$ and have space to store it. Also, make sure your riding mower can drag it around. e.g. level yard. Hills, etc. you probably should have a GT to drag it with.

http://www.drpower.com/power-equipment/leaf-lawn-vacuums/tow-behind-leaf-vacs/prompt-for-ll2-9-59-premier-new.axd?ctm_id=LL2XX9PN&src=AW90388XE3663309&gclid=Cj0KEQjw_9-9BRCqpZeZhLeOg68BEiQAOviWAmuT-QzAC1x-TjYGvWWpyFY4I0ucBz7IfGQvbg6sO60aAnVU8P8HAQ

I had the Cyclone Rake, it folds up for storage if you don't have a lot of room. It has a 2 point connection so it follows straight behind the tractor - not like a trailer, great when backing up. It worked great on my previous yard that had tons of leaves. A little pricy but it is the best. Yes it is a load on the tractor if full of wet leaves.