That is not an unreasonable hypothesis. The WPPSI does have more timed elements than the SBV. The SBV is also not as clearly defined by composite areas (despite the names) as the Wechslers, with a fair amount of spatial and quantitative skill required for many of the so-called verbal subtests, and a significant verbal loading on at least one of the nonverbal subtests (the development team actually had discussions about whether Nonverbal Knowledge should be properly placed in the nonverbal cluster or the verbal cluster, and some studies have found higher correlations between the SBV NVIQ and the WISC VCI than between the NVIQ and the WISC PRI (predecessor to the VSI/FRI). Mainly, though, it's hard to put too much weight on any test administered before the age of about eight or nine, which is why I generally discourage testing in the early years, unless there is a very specific functional purpose for it (such as to tease out suspected disabilities, or to obtain access to an essential resource--and in both cases, only if the child appears to be in distress).
To your original larger question of placement and school decisions, I'll reiterate to take one year at a time, and make drastic changes only when she shows you that there is a meed. There are many factors to school and life success besides pure academic and cognitive development. Given our current educational system, any institutional school placement will entail compromises and trade-offs. The exact composition of those (academic, social, organizational, extracurricular, etc.) will be different for each child and family, and even for the same child at different points.
Does your child feel loved, is she happy, kind, growing and learning as a whole human being? Good enough.
