No hassle at all. We often get called into clients who have implemented OTM and are having performance issues. I'd rather tackle the problem up front by giving advice, than to come into a heated environment where hundreds of thousands (or millions, in the case of the M9000) have been spent.
First, on the OTM Admin guide -- these specs haven't been updated in several OTM versions (since possibly v4.5) and represent the minimum specs to run OTM. Also, keep in mind that the performance per platform differs greatly, as it does with any application. In the case of Java applications, Intel/Linux is currently the best performing platform and offers the benefit of being one of the most cost effective.
The largest problem that your hitting up against is the poor scalability and performance of any 1.4.x JDK/JVM,
except for JRockit -- and JRockit is only supported on Intel platforms. I choose Linux because it's easier to manage and it allows me to allocate a larger Java memory heap than Win32 does. As for the M9000, with current CPUs it doesn't perform very well. With the soon-to-be-released Jupiter class CPUs, it performs well (but not as well as Intel/Linux) up to 4 cores -- after that the Sun JVM fails to scale and 64-CPUs doesn't provide much better performance.
Also, to an earlier comment about the pricing discount for the CoolThreads CPUs -- while this does help, it is unfortunately overcome by the poor PPC (performance per core) that this architecture provides. Now - if I was running an NFS server or a traditional web server (many low weight threads) then I'd pick the T5. I'm not against this architecture, just in choosing the right tools for the job at hand.
With OTM, it is highly multi-threaded, but each of those threads are of significant weight (i.e. highly computational in nature), so it needs a platform that both provides incredible number crunching, and the ability to handle multiple threads at once. Currently, the best platform for this is Intel/Linux utilizing the new high-GHz, multi-core CPUs. Also - realize that a lot of the performance advantage is due to the JRockit JDK, which is much faster and scales better than any other current JDK (currently proven to scale well up to at least 16 cpus/cores).
I have a ton of experience with this (I've been performance testing OTM since the beginning of the product), but I don't ask you to take my word for it. Run the benchmarks and come to your own conclusion
--Chris