My main problem with 64-bit binary is that its one extra compile to do every time you want to release binaries, so you have to maintain one build system for your 64-bit binary and then every time you have to make a build you have to make sure you get both the 32-bit and 64. Really honestly, theres not any kind of significant performance increase. If you have good compatibility youre able to run 32-bit binaries on a 64-bit machine, thats the performance you get. If you run a 64-bit binary, its not going to make much difference. The technology is cool, but theres really not that much point for doing it.