You will be spending a great deal of time with your architect during this process. You need to have a strong working relationship. Is this someone whom you can trust?  Do they listen closely and understand what you are trying to convey?  Are they an advocate for your goals for the project?

Establishing that the architect is someone in whom you are confident is an important consideration when making this important decision.  Talking with past clients is certainly an important part of making this evaluation.