"Since this is not going to be my primary drive and I do not dual boot would it just be better to use the kernel's software raid?"
Ah, I see the confusion. DMRAID uses the kernel's software raid. I've given this before, but here is a simplified version of how Linux used FakeRaid devices.
First off, the case where you're booting from a FakeRaid. The BIOS uses the code in the FakeRaid to read the data off the disks in proper order so that you can boot. During Linux boot, at some point the kernel is loaded to memory and needs to take control of the disk drives - this is true whether it's an IDE disk, an ATAPI DVD/CD, or a FakeRaid. In the case of FakeRaid, the DMRAID software reads what is called metadata from the first device in the array. It uses this to figure out whether the data is striped or mirrored, and configures kernel access, accordingly, and Linux goes merrily along its way.
In the case of not booting from the array, then the kernel once again uses DMRAID to read the metadata and configure access to the array. But, either way, the configuration entails using the kernel's "software RAID" modules to access the array. The difference is that you don't have to get personally involved in actually configuring the array with "mdadm" when you use "dmraid" with a FakeRaid device.
Does that help?