Back in the day...
When I bought the G5 all I knew was that the 1.6 had the same slots as a G4. I didn't research it further than my friends info--he was pretty much alway spot on with stuff like this, so I grew to trust his word.

Recently though having been reading about this stuff there's all kinds of wild stories out there! I've read the same things you've said about the 4 ram slot models and such. I couldn't really tell you either way. I do know that the Digi Mix system worked in the 1.6, and the Digi HD Accel PCI-X works in it too.
I have read that folks with these machines have had troubles with USB devices. This sort of makes sense because USB demands the attention of the CPU, but that's a whole lot of attention! I haven't seen this with my system, but then I may not be pushing it to the same level that they did. I have yet to develop the 192 track style. I grew up with two cassette decks bounced back and forth--I know about commitment.

The SV 4.51 stuff would show up as a single 32K file. So maybe a header would make it, and then fail. I'm convinced it had nothing to do with the DL machine (I tried it on a bunch of them). Thankfully my Gigabit machine had SV on a drive, and as it turns out 4.22 works much better with the Mix system than 4.51.
Probably because I had great access to the Digi stuff (I never paid very much for it) I didn't bother with the TC stuff--because I would have to pay significantly more--and by that on an order of ten to twenty times. Back in the day Digi wanted the employees to own the gear. You actually got to buy it for parts cost. I think the NuBuss AudioMedia card I got before I worked at Digi cost more than any PT system I ever bought.

I don't remember the numbers, but it was seriously low. You could buy one system per year, and everyone bought as much as they could, sold it the next year to buy a bigger system. Do this for a few years and before you know it you have a really awesome system.

That system worked really well when Digi was a bunch of musicians. Once the muggles moved in the company culture went to shit. I didn't last long in that environment. My friends that did got really burnt out. You talk to the people that were there in the early days and compare with those in the later days and you wouldn't even recognize them as being from the same company. But that's probably true everywhere.

Anyway it is interesting that they don't point out the 1.6 in that list. Maybe it is a different animal. As to low bandwidth, on the Digi rig that wouldn't really matter because of TDM. The data is passed along the tops of the cards on their own buss rather than using the computer's buss.
I don't know if it was the fault of the G5 that they didn't support them. The test grid for compatibility was huge, so wherever they could cross a machine off the list and not test it they did so. There were a lot of machines, and bits that ran fine, but were never qualified (officially).
As to the networking. Right now the G5 can see everything. I don't want to have yet another noise making heat generator fired up! But if I do what you suggest sounds like a plan. Looks like I'm going to have to learn more about networking. =8<> Do we ever get to do music anymore?

Oh and...
May the Forth be with you, always.