Blackedout, to answer your question, I have a D&D on my XB12R. Many of Buellers I ride with have Jardines. As with any exhaust mod, you'll also want to open up your intake to let more air in (K&N filter, airbox mods, etc.). The D&D, like the Jardine, is loud and fairly obnoxious, if that's what you like (I do). Both pipes are also similar in that they both lose a little on the bottom, are strong in the midrange and taper off again toward the top. I personally like the torque curve, as it pulls hard in the rpm range where I typically ride. If you look at the dyno charts on ASB, you'll see that the Jardine curves are smoother and it squirts out a little more torque and horses at the very top of chart, and the D&D has a distinctive midrange boost in torque that makes for spirited car passing and launching out of corners.
I think both pipes perform similarly, but they differ in two main areas: price and construction. The Jardine typically needs disassembly and repacking every so often and some of the earlier production runs had some quality issues. I don't know if that's an issue any longer (current Jardine owners chime in). The D&D is built like a tank and has a built in jack plate for lifting the bike. It requires no repacking or maintenance. The D&D is considerably more expensive, but I think my exhaust will last as long as my bike. I don't know if the Jardine would last as long.
Bottom line from me is that both pipes are loud, sound nasty, and make decent power in the mids. The Jardine curves are smoother, but the D&D has a nice midrange rush. If money is tight, get the Jardine. It's a decent can. If you've got some extra scratch, the D&D might be serve you better over the long haul. Either way, you can't go wrong.