There are two primary types of DVRs...
1. Tuner intergrated w DVR: DirecTivo and UTV (as well as the Dish PVR's) record the digital stream directly. The playback quality of the recorded show is the same as the original viewing of the program. Most of these units also have dual tuner setups so you can record two programs at once. The monthly fee for the dvr service is usually subsidized so it is cheaper than the stand-alone option.
2. Stand-alone DVR: The stand alone Tivo, ReplayTV, Media Center PC, etc. all take an analog audio/video source convert it to digital and compress it before storing it on the harddrive. You loose information during this processing... so there is a drop in quality when using the stand-alone units. Also when you use these units with digital cable, or sat systems it has to change channels on an external box which is a bit more of a hassle to setup and it isn't quite as reliable or easy as the all-in-one-systems. However you can use these boxes with any type of service so their flexibility is unmatched.
If you are a directv subscriber I highly recommend the directivo box. If charter has their own dvr I highly recommend that unit... but if you want a dvr that will work with both systems than about your only option is going to be the stand-alone Tivo or Replay systems.
As far as Replay vs Tivo... they both have very similar features and pricing. The biggest issue w replay is whether or not the service is going to be around in a year. The service has shifted hands for the 3rd time in 3 years and I'd be a little leary of it's long-term viability. The original replay box had a commercial skip feature which was great for users but didn't go over too well w advertising firms and broadcasters. Whoever has been running the Replay service has been sued into the ground... this feature has finally been removed from the latest generation of these boxes, so we'll see how replay fares moving forward.
1. Tuner intergrated w DVR: DirecTivo and UTV (as well as the Dish PVR's) record the digital stream directly. The playback quality of the recorded show is the same as the original viewing of the program. Most of these units also have dual tuner setups so you can record two programs at once. The monthly fee for the dvr service is usually subsidized so it is cheaper than the stand-alone option.
2. Stand-alone DVR: The stand alone Tivo, ReplayTV, Media Center PC, etc. all take an analog audio/video source convert it to digital and compress it before storing it on the harddrive. You loose information during this processing... so there is a drop in quality when using the stand-alone units. Also when you use these units with digital cable, or sat systems it has to change channels on an external box which is a bit more of a hassle to setup and it isn't quite as reliable or easy as the all-in-one-systems. However you can use these boxes with any type of service so their flexibility is unmatched.
If you are a directv subscriber I highly recommend the directivo box. If charter has their own dvr I highly recommend that unit... but if you want a dvr that will work with both systems than about your only option is going to be the stand-alone Tivo or Replay systems.
As far as Replay vs Tivo... they both have very similar features and pricing. The biggest issue w replay is whether or not the service is going to be around in a year. The service has shifted hands for the 3rd time in 3 years and I'd be a little leary of it's long-term viability. The original replay box had a commercial skip feature which was great for users but didn't go over too well w advertising firms and broadcasters. Whoever has been running the Replay service has been sued into the ground... this feature has finally been removed from the latest generation of these boxes, so we'll see how replay fares moving forward.