I kind of think that stuff like the iLink is basically for places that actually have the resources and money. I mean, think about it. Just to play two others:
two PS2s turned on
two copies of [the upcoming] GT4
two or more different television sets
Now, an example of having different units playing each other is when I went to two different arcades. Last year, I been to the arcade at Pasadena Town Square in Pasadena, Texas. It had Sega Super GT (to me, the greatest arcade racing game of all time) with another dual unit. So, with certain connections, two dual Super GT units could link together and can all compete at once if they wanted to. It was probably meant for special arcade tournaments. This other one was a few years ago at the beautiful Galleria mall here in Houston. The arcade store around the Galleria skating rink and the big food court featured an arcade place with either 4 dual units or 8 single units of Daytona USA (another Sega game, if you're keeping track). So 8 units can compete at the same time if that was the case.
As far as iLink goes, I'll tell you one thing, GTPlanet. When it comes to questions like online play and iLink play, I'm not as experienced because I'm more old school, plus I'm not really big on them anyhow. One of the hottest multiplayer games I have is Unreal Tournament classic. So I've mostly played against the computer. Now, I like multiplay for some reason, but when it comes to GT4, I'm keeping to myself and maybe to anyone around my way to daresay challenge me to a race. Anyhow, my two cents and then some have been made.