If someone had done the test you want, you'd be able to find it with the forum search feature, or a web search engine such as Google. I'll save you the trouble just this once and let you know that no one has done it yet. That means that you can do it yourself, and then you'll have something to contribute, instead of asking other people to do work for you.
Also, don't use lazy chat-speak abbreviations like "atm."
Does have anyone already tested the difference between 502 Starshatter and 496 Sha-Touche 2H Weapon + 500 str gem dps wise? I can't test it myself atm because I'm on a different computer. Any help is appreciated.