What questions do you have? Limiting the scope of discovery to fingerprinted data is a pretty good way to limit "incidental" data filtering/discovery.
Oh, sorry, I meant questions like the ones raised about how someone might try to smuggle data past such filters or some of the security aspects of having a single point with access to everything.
I certainly agree that if you have a requirement to watch outbound data like this, having a system to selectively capture it is much better than simply attempting to record everything.
https://www.bluecoat.com/products/dlp
“Blue Coat DLP allows you to easily create policies that analyze the data source, content, destination and more.
…
accurate data “fingerprinting” capabilities, in addition to powerful keyword, pattern, and regular expression support, so you can create precision policies to effectively secure your data while minimizing false positives.”
Sure, the every HN reader might have questions about this but I'd bet a LOT of C-level executives are receptive to this.