This is the sort of thing I'm studying this semester - assessments etc. Assessments don't just do reading and writing, they do comprehension and verbal abilities, too. Talk to someone who can tell you about what the assessments involve. The assessor needs to be able to tell you what the tests mean, who the tests are designed for, what they are testing for, what the results mean, what results are 'normal' and which ones mean extra attention is required. The interpretation of results will be used to devise a plan of attack from there. If these things don't get explained to you, keep looking till you find someone who will. Whoever does the test, too, has to help you get a second opinion, too, if you ask for one.
I would suggest to do the testing because if there IS something there, you don't want to disadvantage your DD at this early stage.
It may not be a case of 'too hard basket', and an assessment should sort out what needs working on and what's ok to plug on through school with.
It's not a bad thing if she does need some specialist program help - it may be something you could integrate into normal school, as well. You won't know if you ignore it, KWIM?
I hope it goes well