My younger dd is lower in WMI too although closer to the 50th percentile. Her PRI and VCI were higher than her older sister's, but her older sister presents as more obviously HG and fits in well in accelerated classes with a grade skip.
We've seen some of the same things you mention with dd9 -- spelling and writing inconsistencies especially. She'll use the same word correctly in one sentence and then wrong in the next (their and then there for the same word, for instance). She was able to read difficult words in context, like superfluous, before consistently reading words like "for" correctly. We don't think that she is 2E -- at least the psych who tested her last assured us that she is not.
I would lean more toward supporting her weaknesses in the context of a GT program than taking her out of GT due to weaknesses. Can they write her a 504 or IEP that would allow for some special ed support to deal with her lower memory?
