If your DD is not having problems then there is not much point in having an assessment especially as she is part of a research project at the uni.
They will assess as part of that I imagine- I know someone else who did that.
The benefit is sometimes that in sec. schools children are setted or streamed according to their performance rather than their potential/ability. This is why it is very bad for undiagnosed dyslexics to be in bottom sets if they are bright/ able, but simply have problems producing a good level of written or numerical work.
Children need to be setted according to their ability- not their dyslexia which may be holding them back, Otherwise they become bored, frustrated and either withdrawn or uncooperative.
At a later stage she may benefit from an assessment for career purposes- it will highlight strengths and weaknesses. Also the criteria around exam concessions change almost annually, so it's worth keeping an eye on those; at present sometimes it is possible to have extra time simply with a " history of need" but that usually means being on the special needs register. Additional concessions need assessment and this includes handwriting speed, reading speed, reading and comprehension ages.
The bggest question is- what could the chool offer you if she has a diagnosis? Unless they have a specialist teacher there, then the answer is "Not a lot" in most schools.
The other issue is her self esteem and whether fidning out would help her.
BTW Badvoc and other parents- there have been cases of parents sueing their LEAS , successfully, for not providing appropriate education for dyslexic children. Schools have an obligation to meet a child's needs and if it can be proved that they have not, then some families have been awarded very generous compensation. I'm not suggestion litigation but you ought to know that the onus is on the school to provide suitable educaiton.