So...to throw a little more feedback into the subject. I started wondering a while back, if people have just become too biased against VGT/VNT turbos, and figured I'd make the leap to see for myself with a modern variant.
I'm centering my build (MKIV, 2JZ, fully built engine, titan auto) around a Garrett GT3788va, modified to take a 68mm compressor wheel.
The GT3788va is an upgrade for the GT3782va found as stock equipment in the ~2006 6L Ford Powerstroke.
This model uses your oil pressure and a solenoid to actuate the vanes, using a PWM signal. A company called Fleece Performance makes a standalone controller that gives full tuning control over it. It will position the vanes based on TPS, engine speed, and boost. Limequat is also using this turbo in his 4.2L vortec I6 swap, but is trying to set up megasquirt for control.
As a side note, Fleece also makes controllers for the Holset applications, IIRC.
I cannot remember what exactly the PWM frequency is, but it is outside the range rated for the AEM EMS2's control, so I have no idea if it would be successful.
The 3" vband turbine inlet will also pose a problem for some people, as you'd probably have to modify your manifold or have a custom one made up.
Talking with Fleece, they have had good reliability with this turbo up to EGT's of 1400f, which shouldn't be a problem with good water/meth injection. The weak point is that once you go much higher, the tips of the vanes and the turbine wheel become too soft and start to bend from the force. I'll be running EGT feedback for fuel and wastegate trim, just in case.
I'll post more info up when I get a chance, and again when I get the car running this summer.