One of the problems with using PSEXEC from Metasploit (any of the psexec modules) is that it runs as SYSTEM. What’s the problem with that? Isn’t SYSTEM god mode? Ya, and normally I’d agree that it’s the best level to have, but the defenses these days have gotten better, and getting direct connections out is pretty rare. That leaves proxies, and as you know SYSTEM doesn’t get any proxy settings.
And he wrote a tool to run a process as any user... It's a neat tool to have in your collection. Sources included in his page.