dtrace and any other instrumentation tool for linux require a kernel module as well. Ours has the advantage of being very simple and (in theory!) more stable, because decoding, filtering and scripting run at user level, so you have less chances to crash the kernel.

I would also like to point out that the sysdig workflow is quite different from the drace one. In addition to supporting real-time investigation, sysdig lets you take a rich "snapshot" of the machine activity that you can analyzer later. From this point of view, I don't think sysdig is less powerful than dtrace. Quite the opposite. But we're eager to know what you think.

Is dtrace available on Linux? I know there's been work towards that goal, but I haven't payed much attention to it recently.

It's "out of tree" due to licensing issues (i.e. Oracle is not releasing it under a GPLv2 compatible license for various reasons...)