Re: 'Most research is sponsored by proprietary software companies, and as such might be biased'
I don't believe its possible to find an independant expert, and for that matter I don't even believe its possible to make a fully informed rational decision about these issues. I always considered it to be an almost religious decision made on faith. Certainly IME that was what was going on where I worked.
But I'm rather of the opinion that if you have your support staffing and training sorted out it probably doesn't matter too much what you use - and if you havn't got your staffing support and training sorted out it probably still doesn't matter.
But as others have said I am sure the key issue will have been support for specialist applications. IME they will be Windows only, and anything away from a pure MS environment will greatly increase the amount of resource you need to put into the specialist apps because the vendors won't. Use different vendors? Its hard enough finding a competent package for these jobs anyway without excluding from consideration all the ones who won't support a multi platform shop. We're there to serve the users and deliver them the best working environment...