They are really two different things - Solidcore is all about unwanted change control, DLP is about content based user behaviour modification. Solidcore won't stop you copying a file to a usb stick, and DLP won't stop you changing a registry key.
If you need an environment protected from unwanted changes, like an ATM, POS or a compliance sensitive environment, plus you need to stop data leakage, you'll need both solutions.
I've a hands-on training tomorrow by McAfee on SolidCore Products. At present we are using scriptlogic File System Auditor for file integrity reporting. Where can I get demo version of testing purpose?