Conclusion
OCZ's PC3500 Gold GX performs quite well for the price, however naturally you should not expect the same level of performance as you would get from their top of the line PC5000 product. I was pleasantly surprised that we were able to run the memory at effectively 450MHz as it was stable at 225MHz, providing a small but appreciated boost from the 433MHz it is rated for.
We had no stability issues with the memory (except when we tried to run it at 1T timing, for which it is not rated) and the performance was quite good for the price.
For real life applications, it would be rare for you to see more than a 2% increase in speed from using the faster memory; ofcourse you can see higher results for memory benchmarks and scientific applications that are memory bandwidth bound.
For those gamers looking to sqeeze out the last bit of timing performance without paying for PC5000 memory, the PC3500 GX managed a fairly impressive 2-2-2-5-2T at 225MHz.
Recommended.