I think it would be useful, and honestly, even if they are very well-intentioned--I would want information and expertise beyond what the school district could offer.
Dr. Beljan is very, very knowledgeable about giftedness and dyslexia (also ADHD/Executive Function). Even if you aren't anywhere near him I have corresponded with him and I am sure he would be do a phone consultation to share the benefits of a neuropsych eval, how to find the right dr., etc. He has at least one lecture on youtube where he addresses dyslexia/giftedness.
Edited to add: re: hiring an advocate--while there may be a time...I wouldn't begin with it. Sometimes it can set off an adversarial relationship when the school would have been in fact willing to work with you without hiring an advocate. Pete Wright did suggest bringing a clergy member once though! Honestly before an advocate get the book From Emotions to Advocacy. If you do everything in that book I don't believe that it would come to the point of needing an advocate.
http://www.paulbeljan.com/I think an eval. could provide useful information that could help you advocate appropriately for your child.
