If you think the tool could be improved, provide evidence from combatlogs or calculations to demonstrate this so that the author can make corrections. Just saying "I don't trust it" isn't actually constructive.
I really dont think that the simcraft data is correct in terms of dks. It uses completly different data than consider provided a few weeks ago and I dont get how this should change via a 12% increased melee attack damage. That said simcraft simulates 26317dps for my current gear setup, which is resulting in over 1k more dps using this profile chardev profile chardev 8 - Cataclysm Beta
This tool undervalues haste in both specs, frost and unholy, thats why i wont use it till this is fixed.