First test on my daytona setup was good, although some questions remain.
Indy 500 with the ROM patched, (but without the new link fix) works good, as long as all machines can keep up with 60 FPS. - It gets even worse than Daytona if machines can't reach full speed. - Most of the time I try to overtake an NPC car, they instantly "teleport" into my car and crash me.
With the new link fix, that doesn't happen, but the game will slow down for everybody to the lowest machines speed. (which is fine if they can run at 60fps)
I still can't get a "reasonable" netplay in Sega Rally though, even with only 2 machines and the link fix, the timers go crazy. The problem seems to be buried deeper inside the network boards.
Haven't tried other games yet.