PcPlayer Direct3D Benchmark
The benchmark reveals the Quantum 3D cards to be almost 20% slower with Direct3D games as you could already see with the Incoming and Forsaken benchmarks.
At 800x600 the performance gap of the Obsidian cards decreases to approximately 10%.
Direct3D doesn't seem to be the domain of the Obsidian cards (or at least their drivers). The top model X-24 is clocked at 95 MHz and runs quite a bit slower than the others still.