I am running several stress tests at the same time against different systems which share a database server (That's also the production setup). My problem is that I haven't found a way - except SQL Profiler - to gather SQL Server usage statistics per database/database user. I want to keep the mix, but on the other hand I want to identify the parts of the application which creates high CPU.
Is there a way to monitor i.e. CPU per database / CPU per database user with the SQL Server monitor?
I've often found it useful to engage a DBA resource to monitor the databases in detail. The test as you describe appears quite complex, and, unless you yourself are a DB Wiz, it's likely that any conclusions you draw will require confirmation from a DBA anyway.
Get them to slap on their monitors, traces, profilers and figure out what is going on. Focus your attention on setting up and executing a realistic test.
It's fairly common for people to assume their tool of choice is able to 'do it all'. It's pretty much a bad assumption. Either the setup to get the tool to give you what you want is time and $$$ intensive, or the capability is incomplete, or the technical expertise required to understand the output is beyond the pay grade of the typical tester.