Perhaps PC could be improved for GT learners (it has the lowest reliability scores of any reasoning subtest for GT, and GT is also the subgroup with the lowest reliability for PC), but since it didn't turn out to be a preferred subtest for the core, it probably wasn't worthwhile for Pearson to invest more time/money into tweaking it.
The simplest answer to why the EGAI has BD and not VP is that it was derived from the original standardization sample for the GAI, plus the two extra verbal comprehension subtests. It's not entirely clear why BD is in the GAI/FSIQ rather than VP, as their psychometrics are similar, but I suspect it is because BD allows the clinician to observe the externalized process of solution development, and it historically is a good rapport-building subtest with which to open testing.
I would not describe any of the subtests as spoiled or inflated. It's more a question of how one interprets the scores than of tossing some of them out (except in the case of those where standardized conditions were broken during administration). Also, the highest-reliability index scores do not allow substitutions (one is allowed for the FSIQ, but that's it), so picking and choosing subtests would result in less--and less reliable--data, rather than more. The more relevant factors for an imminent WISC in your case would be:
1. to make sure that the examiner knows beforehand that you and your parents are interested in the Extended Norms, if they are applicable (so that the examiner does not prematurely discontinue any subtests after reaching a max scaled score, and so that they are more likely to calculate ExN scores if needed);
2. to discuss whether the EGAI will have value to you; and
3. to include your specific concerns about your executive function development and possible ADHD in the intake, so that they can select appropriate measures.
