And what exactly do you want to sequence with that step-sequencer, since the only thing you want to have running besides the step-sequecer seems to be Traktor (and as far as I know Traktor isn’tparticularly suited to being step-sequenced…)?
A step sequencer isn’t what you need, since the only thing is does sequence other devices and does not play any sounds itself…
You need a full grown drum machine / groove box that works standalone (not just as a plugin). Products that come to mind are said Maschine and FXpansion Geist, but neither of them is exactly “lightweight”…
Maybe the Artutia Spark or SparkLE? I doubt you can control it with your launchpad though. If you really want to use your launchpad, you’d probably have to use A max4live device.