Sorry for the delay--been busy.
I'm using Milestone with two Dahua 1080p cameras, with plans to add more in the future. Milestone seems to be running fine, and I have no issues viewing the feeds via the software or the mobile app on wifi. On cell service the quality drops, but that is to be expected. I haven't passed through a GPU, but I'm not totally against the idea. I recall that it helps with the video rendering, but I don't know if its worth it for only two cameras. About the only complaint is that it generats a ton of video footage, as I record 24/7.
I just finished setting this up, and that's the way I decided to go. Seems to be working great. Just gave the disk a name of 'security' and shared out the whole thing.