Spyder, I'm a big fan of the Brisnet product myself. IMO, theirs and Trackmaster are light years ahead of DRF, and it has nothing to do with the speed figures they produce.
"Sheets" are produced by two competing companies who were once together. Len Ragozin was the innovator and can be found at
www.thesheets.com. Thorograph was started by Jerry Brown, a former employee of Ragozin. I don't know either guy, but everyone says Brown is a better PR guy if nothing else. He lets you view a "Race of the Week" for free and has a lot of other promotions to get you familiar with the work at
www.thorograph.com. Ragozin wrote a book about his work which was basically a 200 page commercial for his product with zero insight. As a sidenote, Cary Fotias uses sheet format to produce his "X-tras" product which uses a lot of the same ideas the other sheet guys, but takes it a step further by incorporating pace figures on his sheets. I'm just learning his stuff, but the early results are promising. Both Ragozin and Brown speak of pace as having an insignificant effect on most races(whatever works for you- I guess). Fotias is at
www.equiform.com.