CableCARD tuners are the biggest disappointment to me since I discovered that there is no Easter Beagle. Granted, the magnitude of the horribleness of the experience is greatly influenced by your provider, but in my case, I would rather shave my head with a cheese grater than put another CableCARD tuner in place as part of my MCE setup. Here are the top 2 issues that I encounered:
1). SDV. Time Warner and other providers have implemented SDV in their signal delivery architecture. This presents them with the opportunity to provide us with a wonderful piece of technology (not the first noun that came to mind) called Tuning Adapters, which are required for OCUR CableCARD devices to work. The Cisco TAs that TWC provided locked up 3 times a week and just completely made life hell.
2). DRM. This is the major turd in the punchbowl. Period. If a program has a 5C flag of anything other than Copy Once, that recording is completely locked down. It can't be played on any other pc, commercial skipping applications cannot analyze them, they cannot be burned to dvd....they can only be played back, and only on that computer, in the same condition in which is was recorded. Of course, time warner flags everything except the locals as Copy Once, completely crippling any CableCARD implementation.
I've gone to a dual HDPVR setup using DVBLogic. This allows for completely DRM-free recordings, tuner sharing across my client PCs, and a very happy MCE setup, regardless of my provider.