It realy isn't a question of Evo vs BB, but Android vs BB. Android OS can handle Exchange email just fine, but there are some definate limitations, at least there were in Android 2.0. You can't search exchange email. I suspect that will get fixed in later versions of Android and I am hoping in 2.1 it will.
BB is the best business phone period. However, I am seeing more and more key business features in Android now, so I will be making the move to Evo this summer. Does your company use Citrix? Check with your IT dept and see if they do. If so, ask them if they deliver Outlook over Citrix. If so, then you can probably talk them into letting you run Citrix on your Evo and get the full Outlook right on your phone, which is better than you can do with BB.
I hope this helps and if you need more info when the time comes, just PM me.