Yes, Scala's improvement from 2.9.2 to 2.10 is better than the improvement from JVM 6 to 7 with this benchmark. Especially for the Eratosthenes test where the time halves from ~1494ms to ~704ms.
The largest percentage improvement from 2.9.2 to 2.10 is therefore roughly 52% (with JDK 7 and 2.10 over 2.9.2). The largest percentage improvement when comparing the JDK versions however is 13.85% where the JDK 7 sundaram test with scala 2.9.2 runs faster than JDK 6 with the same scala version.
