There are two distinctly different styles of slippers currently on the market for the 1098/1198; Ball bearing and constant spline. The benefits of a ball bearing slipper is the ability to adjust how much slipping you get. Its very hard if not impossible to make those adjustments with a constant spline slipper. The whole purpose of a slipper is to match the revs to the rear wheel speed after a downshift. Some bikes take a lot longer to make this match between revs and rear wheel speed, others are a lot shorter, based on displacement and weight of the engines bottom end. Ducati's are notorious bouncing around because the bottom ends are heavy and the motor simply doesn't want to change revs so quickly, this is why slippers are so important on Ducati's, especially the big bore machines.
Bucci, TSS and STM are the leading brands from Italy who make ball bearing slippers. Rumor has it, the DP clutches are made by Bucci. They use very soft aluminum baskets/hubs, which do wear out extremely quickly on a racing bike. The STM clutches use a much newer style of ramps and bearings, which is quite clever.
EVR is currently the leader in the constant spline design. The EVR clutch is one beautiful piece of art, its masterfully created and looks like it would be a great slipper. Unfortunately, its non adjustable, so if you want more slipping, you can't change the stack to make it work.
I used a TSS clutch for years, bought it from Motowheels, but they stopped importing them for some reason. The Ducati performance clutch is probably the widest used, easiest to find example, even though the stock plates it comes with are garbage. The best plates are made by surflex, they have a single friction surface and NOT individual spaced pads, so they're easy to find if you look at pictures. I have yet to try other clutches with anywhere near the same results. EVR's plates weren't too god awful, but for sure nowhere near as good as the surflex. Wish I could still find those surflex plates…
If you do a google search for the companies and products I talked about above, you will find distributors for them. Its unfortunate Motowheels doesn't sell the basic slipper anymore because thats what I'd buy in a heartbeat.
Hope that isn't too confusing!