As a matter of fact, yes I have done all of the above. We work with Digibeta most of the time, but have a need to capture DV25 material as well. I have two way to do it. Through a Panasonic AJ-750 with an installed SDI card or through a small Firewire Deck. The Panny will “upconvert” to 4:2:2 color space. We tried each method, via the Panasonic deck and via the Firewire deck. No descernable difference in either case. Both were virtually the same. Actually, the Firewire transfer actually looked a little better for some reason. One less cycle or conversion to/from another format?
There is only so much information available in a DV25 signal. It’s compressed 5:1 at the source and recorded that way. Playing back in either case uses the exact same information to begin with and does not “add” any additional information to the signal. It simply increases the sampling/data rate used to describe the information that already exists.
A good analogy would be to take an MP3 audio file, a highly compressed format, and drag it into iTunes or Quicktime Pro and then export it as an .aif file. The result is a file much larger than the original MP3. Has quality been gained or “synthesized” in the process. Nope, the “higher quality” .aif will sound virtually identical to the original MP3. Nothing was gained. Your are simply using more data to discribe the original MP3 file. It simply is not going to sound better just because of the bigger file size.
The same applies to converting a DV25 data stream into a higher quality datastream. You are just using more “bits” to describe the original data. No new information is being synthesized in the process. Now upconverting is another story where new information is “made” by interpolating points between existing data points. It isn’t really adding real extra “real” quality, but it does appear that way to the eye and results in both a larger file and usually a larger screen size or resolution..
Anyhow, this is one of those topics that has been discussed endlessly in various forums here. All things being equal, there isn’t going to be much difference in either method. Now I won’t argue that all codecs are the same. There can be noticable differences there. The Apple DV codec is much improved over it’s earlier versions, but there’s always room for improvement. If there’s any difference , that’s where it might occure.
BTW, Apple writes all the drivers for the AJA Io. They all come out of the same place.
All I’ll add is if it works for you and fits your workflow, do it. This is simply one of those topics that everyone will never be able to agree on.
Tom