has anyone benchmarked Excelsior JET compile-to-native against a standard java runtime?

DISCLAIMER: I work for Excelsior.

To answer your question, the most recent third-party benchmarking results that I know of are these, but I've just checked - that post is over four years old...

Now if you allow me to provide some advice:

Based on over 13 years of Excelsior JET market life, I can tell you that you have to test it against your particular application. No benchmark will give you any idea how your app will behave when natively compiled. As we say, your mileage will vary. We have customers reporting increases in speed that we've never seen in our lab, and we have prospects abandoning their evaluation early because their apps become much slower. (The latter often happens due to misconfiguration - e.g. not all classes get precompiled - so please contact our engineers if you run into something like that.)

There are also some case studies with performance comparisons on our Web site (#1, #2), but of course those are from users whose apps became faster. ;)

Update 15-Dec-2014: A word of caution: As of Excelsior JET 10, the 64-bit version is lagging behind the 32-bit one in terms of performance, as the former is based on the new, built from scratch compiler core that has less optimizations implemented. We are working hard on reversing this situation, but for now, if performance is important to you and you don't have any really good reason to use the 64-bit version, such as large heaps or the need to integrate with 64-bit native libraries, or the need to target OS X, stick with the tried and true 32-bit version.