What tests are they proposing to administer? I would ask for a list ahead of time and double check that you are getting what you want out of this expensive testing. IQ testing alone will not be definitive re dyslexia. Here's a link that talks about various tests and how they can be used to identify dyslexia. It also has a link to a document about dysgraphia testing.
http://www.concordspedpac.org/Whichtest.htm
A neuropsych eval also may identify other potential causes for your child's issues that present with similar symptoms.

Thanks for the link, it was very helpful.

Hi Bella,

My son's IQ was initially measured at 144, but his processing speed was considerably lower. We have just been through another round of testing (four years later). I am waiting for the IQ number, but from what I've seen (before the final calculation), it is significantly higher. However, his processing speed remains low.

He makes the same sorts of errors that your daughter makes, and he has been loosely labelled 'under the umbrella of dyslexia'. I saw it before his fourth birthday, but of course nobody will identify dyslexia in a child so young. Highly gifted children will find ways to make up for many of their deficits.

I suggest you read this article on 'stealth dyslexia'. I discovered, myself, just last week. It really opened my eyes, and helped me to finally understand the challenges my son faces. I wish you all the best.

http://www.davidsongifted.org/db/Articles_id_10435.aspx