Whatever you choose, if the results make no sense, question their relevance.
Yes.
Additional info: the DAS-II has a different structure from the WISC-IV, with three primary clusters feeding into the global measure, consisting of verbal, spatial, and nonverbal, roughly equivalent to the WISC GAI (verbal, perceptual reasoning), where perceptual reasoning is a mixed measure including one spatial and two nonverbal/fluid reasoning subtests.
The DAS nonverbal subtests are not quite like the WISC, though each has a matrix reasoning task. The DAS second measure is a quantitative reasoning subtest, while the WISC second fluid reasoning measure is a concept formation task using concrete images, which is highly amenable to verbal mediation (so it's not a pure nonverbal measure).
The DAS spatial tasks consist of a patterning task comparable to the WISC block design subtest, and a fine-motor copying task with significant visual memory component, which is unlike most of the WISC, though it might have some relationship to some aspects (fine motor) of coding from the PSI. I usually find that it lines up fairly well with the Rey Osterreith (RCFT) copying task. If you have a child whose specific weaknesses are in visual memory and fine motor skills, it is possible that the DAS spatial cluster would be lower than the WISC PRI for those reasons (though one would expect similar depression on block design).
The main reason for the even profile on the DAS vs the diversity on the WISC is likely the fact that the DAS GCA is essentially the same idea as the WISC GAI (with above caveats), so the (auditory) WMI and PSI aspects have already been removed from the profile. They are supplementary/diagnostic subtests only on the DAS, while they are counted into the FSIQ on the WISC. If you wish to compare results, the GCA should properly be compared to the GAI, the supplementary recall of digits to WMI, and speed of information processing to PSI.
And may I gently remind you that it is possible to get less than optimal performance not by design. Sometimes rapport is not established effectively enough. Many GT examinees also pick up on tells from the examiner, and alter their performance in response to perceived success or failure. An examiner who is inexperienced with DYS-level students (which, statistically, must be most of the ones not employed at gifted centers) may inadvertently generate flawed results because of this or other factors, such as not knowing how to score unusually creative or divergent (but correct) responses.
