If you only pursue one avenue for evaluating an architect, it should be this one. After all, everything else is wrapped up into this final outcome.
Ask for a list of references, prepare a list of questions, and call them. They have been through what you are about to do. They will have a perspective on most of the other criteria included in this overview, and can offer a frank assessment of the process and the product.
Read KIND WORDS about Nautilus Architects