In my quest to find an answer for whether or not to do the neuropsych, I came across this recent article. Here is a relevant excerpt:
It is extremely difficult to evaluate the cognitive abilities of individuals with RTT as these are masked by their motor, apractic and atactic difficulties, which limit normative evaluation. On the other hand, many research projects have suggested that individuals with RTT are able to learn [18-21], and that the learning skills can be enhanced with appropriate motivational factors  as well as that learning is sustained after a ‘washout’ period of the learning program has ended . It is also clear today that individuals with RTT can learn new skills [22,23], including literacy [20,21,24], and that learning ability is sustained in individuals with RTT at all ages.
The article is insightful in many levels and the premise is basically that girls and women with Rett Syndrome need intensive and constant therapy/intervention throughout their lifetime to maximize their quality of life.
I’ve seen the positive effects of intensive intervention firsthand. And there is now some data to demonstrate that Lily is progressing both motorically and cognitively. For example, her first progress report for the year has come in and it is the FIRST TIME that the teacher at school has indicated that Lily has made significant progress in a few areas. It is most definitely because she has a Tobii at school now, and that her teachers and therapists are committed to engaging with her through it.