I have an Embroidery Machine Comparison Chart from 2007. It came out of a Creative Machine Embroidery magazine (but I don't know which month). It says to visit them at sewnshop.com. Maybe you could look for it at their website.
Sorry, I don't know of any written reviews for you. I suggest you contact any local embroidery companies and see what they use and how they like them. Or go to a shop that sells machine embroidery supplies and ask them to recommend someone that does commercial embroidery, then contact those people directly and ask questions. I know many in my area use MELCO but that's all I can tell you.
Good Luck!