Also, I took a screenshot of where the interchange begins to fail, you should be able to see it in the Artwork section of my profile. b

Hey dude,
I've had a chance to run this interchange through my 8-way torture test now. It was performing well, but there is a kinda fatal flaw. It's the lane exiting the roundabout, it has to mix with the "first-right-shortcut" before it gets to the highway, when these two lanes mix it can start to cause a backlog of traffic. I'm not using priority signs, so this soon backs up onto the roundabout, pretty soon the whole roundabout comes to a halt. What it really needs is for the traffic exiting the roundabout has it's own dedicated path to an empty lane on the highway to guarantee that the roundabout remain clear.

A few other comments.
The inner cloverleaf style shortcuts are only used a little bit, but are probably just about worth it because it takes vehicles off the roundabout that would otherwise be on the roundabout for a long time.
The performance still was not terrible, it would come around the middle of the pack in my 8-way intersection face-off

Very impressive, and not just from a "looks awesome" perspective. The "short-cut" routes look like they are very well thought out and the way the traffic enters and exits the roundabout looks like it will avoid a lot of congestion problems. I've subscribed to it and will be running this through my 8-way intersection test when I get a chance and I'll report back here when I've had a chance to play with it in detail.