We received the same Thoroughbred CPU to our testlab which was seen at the Cebit 2002. The core of the CPU is built on 0.13µ process technology and it's considerably smaller than the 0.18µ Palomino core. The surface are of Thoroughbred core is 80mm2 and Palomino's core is 128mm2. It says "Mechanical Sample" on the top of the T-Bred core. There is also a sticker which says AIQAA-stepping and 0204. This means that the CPU was finished at week 4/02.
I installed Thoroughbred to new Epox 8K3A+ motherboard and turned the power on. Everything went fine although 8K3A+ didn't recognize Thorougbred and said it was Unknown CPU type. Default multiplier seems to be 11x so the CPU was working at 1466MHz clock frequency. PR-Rating would be equal to 1700+. I don't know the offical Vcore for Thoroughbred but I adjusted it to 1,65V. System booted fine to Windows XP.
I ran few tests and didn't face any problems. Unfortunately I can't tell you any benchmark scores but since there are no differences between Palomino and Thoroughbred than manufacturing process, it shouldn't be too hard to figure out that there are not much which could bring more performance.
The next thing I tried, was overclocking the CPU. With 1,65V Vcore I was able to reach 1550MHz. With 1,75V Vcore I was able to pass all benchmarks when the CPU was running at 1600MHz (equal to 1900+).