I honestly dont think the reliability will be any better. The stresses you will be putting on it will be different to how it will be working in a CCTV. If anything it could be worse.
CCTV is a slow addition of video feeds over normally an hour and multiple feeds, so for instance if you had 4HD cameras it would be slowly recording and rendering in hour sections 4 separate feeds, then a new file is started.
While write speeds might be a little better maybe, and that could be argued, Read speeds maybe terrible, I have not had to take footage off of a CCTV HDD in quite a while about 4 years maybe, and that was through USB 2.0 so i cant tell you for certain. The whole point of CCTV is write speeds it does not matter how long it takes to show you that footage as long as it records well.
Id take that into consideration too.