while i agree the dvr 8300 hd sucks big squirrel nuts, i can tell you from headend knowledge that for every frequency there are 2 hd channels put into the bandwidth. There are however a few exceptions, TBS HD is one channel that has 3 maybe 4 channels in their respective frequency......however, the ONLY reason for this is that most of the programming TBSHD sends cablevision is not in HD, and your tv needs to format it, same holds true for other channels like HGTVHD, etc. The poor picture quality has little to do with cablevision and mostly lies fault in these respective channels feed to CV.
As for slow interactive features, you first need to find out if your box has an ip address....(reply for instructions on how to access this if you dont know). If your box does have an ip, pull out the card and see if it has any burn marks on the reverse side of the chip, if you pass all of the above diagnostics, you may need a box swap, components do fail over time, as im sure you know.
As for slow channel changing, see the first sentence of this reply.
I have to say that all of these problems are so minor I cant see myself getting mad at CV for them, my picture pixelates more than normal, I know what the problem is, I just dont pay it much mind, bc i dont get mad at the petty sh*t, CV offers a good service for the price, and if your complaining now, wait til you get your first fios bill when you switch, I switched right back to CV after I got it. To put it simply, the grass is definetley not greener on the other side. The picture with fios is better, but poor customer service, expensive bills, and an internet that is so lagged with problems it made CV look iconic made me come crawling back to CV, and they welcomed me back with open arms and a 2 year promotion package.