Based on your post, I went to Rogers on Bloor yesterday and bought one. I love the simultaneous SD output because I have a Faroudja NRS scalar, which I couldn't use with the 8000HD, but can with the 8300.
Subjectively, I find its PQ better than the 8000, but haven't done enough critical watching to say for certain. So far, I'm much happier and am returning my rental 8000HD.
There's a new recording option, from the same channel at the same time, when recording all episodes. Not as good as recording only the first showing, but a small improvement.
I've noticed the hard drive is much noisier than the 8000HD's. I hear the actuator a lot more, even when doing a channel change. When powering it on, it does the same. I wonder if it powers down after it's been idle for a while.
I read on SA's web site that the 8300 is supposed to act as a video distribution system, but don't see anything in the provided documentation. I was under the impression that you could pass a recording to another cable box located somewhere else in the house. Maybe I don't understand it correctly.
For others reading this, we have SARA in Toronto.