ODE Physics Benchmark Setup

Hi,

I was wondering what the best ODE configuration would be in order to 
achieve:
a) The best accuracy (in terms of following the ideal physical models)
b) The best performance (in terms of computational efficiency).

In particular, I am referring to:
1. Which "stepper" to use (at the moment, I use WorldStep)
2. How the dSpaceCollide callback should be structured.

(the application(s) which this would apply to are the PAL benchmarks : 
http://www.adrianboeing.com/pal/benchmark.html#benchmark, so friction, 
restitution, links, etc are all important for the callback)

Thanks,
-Adrian