A lot is determined by what you are looking to do with it.
If using the guide data is a big issues, you may want to see if the Canopus card is supported by some type of PC scheduling software or if they provide the drivers to write your own.
Hardware based deinterlacing while recording is available on some cards, as opposed to the Replay that does it on playback. The Replay also produces a dirty MPEG that may have to be -cleaned up- to use on some other applications. A plus is that the Replay MPEG does embed the Closed Caption data so that the MPEG file can be mined for rich media content applications.
I have been unable to find the specs for the Canopus Amber (or a Search button) on their US site this morning, but you may want to check on the interlacing issue and MPEG 4 recording options. If the card does not provide them or they are not really issues then a better/cheaper alternative is the Hauppauge PVR-250. If has excellent video quality, a built in stereo tuner and sells for $100-150.
The PVR cards provide much more color depth then older (ShowStoper/4xxx series) Replays when recording from the tuner. (I have not really compared it to the 5xxx.) It provides hardware encoding of Mpeg 1 and 2 at up to 12MB CBR/VBR. Using freeware drivers you can put multiple cards in a single PC.
The cards do NOT embed CC data, de-interlace or record Mpeg 4. The Vendor software interface was initially very poor although it looks too have improved. The 3rd party command line interface is a snap and there is support for free/commercial schedulers.
The Replays can record Macrovision content. I have not tested the Hap-PVR card for this.
While I do have nine Replays (only 6 in use), I really like the PVR250s and have used them in several PC recorder applications. (3 Cards recording 6-8MB VBR streams uses causes about 2% CPU utilization on a 2000+ AMD with a 1TB software defined raid.) The systems can be configured to auto convert the files to Real or Win Media and provide streaming web access. By mixing them with a low cost ATI card I can build a system that will allow web based keyword searching of transcripts.
Using the Hauppauge MVP media nodes ($80-100 each) up to 12 remote MPEG playback set-top streamers can be added to a single PC server, and thru it access networked storage. (I have not tested the 3 card encoder with more than 4 physical and 4 simulated streamers at once. They provide excellent playback as a set top box (about the physical size of a 4 port hub.) and can play back content as it is recording. The nodes can also provide palyback of Dvix content on one node at a time by transcodeing the media automatically on the PC. The user interface is done via a HTML and can be customized by the user if they are willing to work at it.