The price is about the same in the end. With the super low cost finger style units, they usually need a modified or aftermarket cover which can get pricy. I don't think there is enough room for the finger style lock up to work behind a Duncan cover. There should definitely be enough room for a sling shot though. I do not know if it's actually big enough to pull off the service cover of the sling shot that I run though. Mine is from Lane at Driveline. It's tits. The first season I had it I didn't mess with it much. I set it up according to the directions, and learned what it did to the bike in different situations. Then I started messing with the weights and making it slip for just the hole shot and that made a huge difference on race day. Then I started noticing it engine braking a bit less aggressive, the weight on the rotating mass (yep thackism) seemed to help the bike coming out of the apex of the turn. Couple that with the fact that it seemed to slip just a cunt hair out of the turn so I started using less clutch fanning. It made the bike retarted predictable. I'm sure a finger style could probably be tuned to work as well, but I kinda dig my driveline lock up. Newest venture this year has been different clutches and weights from McMaster Carr
Buy one^
Also, have CamATV cut your trans....