Sorry I'm a bit late into this thread...
Most mechanics frankly don't know [anything] about the Teves system. As we have 3 Reattas, all with Teves', I'm pretty good with them. Rarely does the Teves master cylinder have to be replaced. If you do have to replace it, Prior remans them with new pumps and pressure switches for $600.
The Reatta board users push for Teves owners to flush/bleed the system every 2 years. Initially, you'll want to either drain the resevoir from the hose in the back of it or suck it out a couple times to get the old crud out. The fluid circulates inside.
Above is a link to Reatta.net Teves brake tests. This is able to pinpoint most any Teves issue, except with the wheel sensors or possibly a bad ABS computer. There'* more about the system at Reatta.net under "Brakes" as well.
A Reatta owner was recently quoted by a dealer $6k for Teves brake work