Take 2... er... 3...
Not that this will matter to anyone at this point, but maybe down the line for another DOTD/Lightning Deal.
I have one of these and the original Hauppauge HD PVR for my Core i7 model iMac (upgraded from the EyeTV 250+ and EyeTV HD when I realized I could record HD game footage with them).
The advantage of the original model HD PVR (the component-based one) is that, using EyeTV 3.X software, it has direct A/V and S-Video input (if you're using that), as well as an optical audio-in port. You can customize the rate at which you encode the video and the audio, and record them to a proprietary EyeTV format to then export to dozens of different file types. It will also output back to your TV through component. You can run your cable connection and pretty much anything from PS2 up through the 360 on it with component or composite. (don't have a Dreamcast or Wii U, so I can't try them).
The Elgato Game Capture HD will also let you use it with EyeTV 3.X software, but you can only choose "1080," "720," "Standard" and "Mobile" preferences for encoding, but have direct brightness/color/contrast/hue correction options that you don't get with the Hauppauge HD PVR. Cable (at least for me) will not be recordable through HDMI, but it can be over components. And, again, you can export to all different file types.
The Elgato Game Capture HD on it's own proprietary Game Capture HD software that you can download from the Elgato website will pretty much let you convert anything to an mp4 file, with adjustable compression and color settings. Not only last and current gen consoles, but as of earlier this year, Elgato updated the firmware for legacy systems using 240i/480i output, so that consoles like your SNES and Genesis and PS1 and N64 will run on it to. I even hooked up my Master System 2 and TG16 through co-ax to my DVD/VCR, outputted via composite through splitters (one to the Elgato and one to the TV directly) and it recorded it just fine. The only issue with this may be that many HDTVs will not recognize a signal lower than 480p through HDMI, thus the need for me to use composite/component splitters to send it to my television that way.
You can also record audio via mic directly into the recorded gameplay video, and it is set up to sync with your Twitch account and they have recently added some Youtube streaming capabilities. And you can record cable programs via the component connection (it still won't recognize the updated HDMI standards for blocking the signals).
Though, there are a few odd things I've noticed about the game capture abilities... the Elgato comes with it's own proprietary PS3 connector cable. Something in the PS3 (at least the last time I checked) will not allow it to use standard HDMI output without experiencing some issues. Xbox 360 I have used with both the HDMI and Component cables, and both seem to work perfectly fine. Both the proprietary PS3 cable and component cables are detachable and plug into an S-video-like serial port on the device (an S-Video wire is not included, but can be ordered separately).
Also, the legacy systems, when recorded, seem to be cropped around the edges a bit for some unknown reason. It seems like you're only getting 95% of the video screen with a black border around it, and the imagine is being slightly compressed. Though, there is also an option to stretch the video in standard mode to make it widescreen by default.
File sizes though... and this is the biggest oddity. You are given the option of recording as "Source" or not. I always select to not record as the Source, as I notice it tends to leave me with ginormous files for my legacy systems. Also, you can record something and if you're recording cable and you change the channel from a 480p to 720p or 1080p source, sometimes the device will automatically end and restart the file, and you sometimes you can record something that is 2 minute long and you end up with a 6.3GB file or something like that. I'm not sure what is going on there, though the raw file is often re-encoded into an output file upon stopping the recording and will show up briefly in your folder for 30 seconds or so (Elgato recently updated the firmware to help battle the problem. It has been greatly reduced, but it is far from eradicated).
I have noticed, however, that when I do get a random obscenely-large file sized video that does not match my other videos and I know it needs to be lower, I drop the video into SimpleMovieX (a free editing program for Mac) and trim away a bit, and it seems to reformat the entire file down to the normal size it should be.
Outside of that, I haven't had any problems of "recording black" or off-sync audio as the poster above me had. I really haven't used the mic-to-video feature much, so I can't speak for the prevalence in those types of videos. But I've yet to encounter any audio issues at all with mine.
Also... both the Elgato and Hauppauge HD PVR let me record VHS footage, too. If recording with EyeTV software, the Hauppauge looks better overall, but both devices hate video head static and it will distort or scramble the recording if it appears on screen. (I think this is actually the EyeTV software and not the devices). The Elgato, however, running on the Game Capture HD software, seems to record pretty much anything I throw at it, tape static and all. Old recorded game footage. All the sub-SD crap my bad 80s/90s television connection would throw at me.