I think you're thinking of Hollingworth when you mention that social issues occur over IQ 150 (I think she actually wrote 155). That was based on older ratio IQ tests, which tended to give higher scores than the newer IQ tests. However, the basic point is the same. Kids at the farthest tail of the distribution are more likely to have social challenges than those closer to the middle. On modern IQ tests, it is rare to score over 150 without extended norms.
Some kids who score in the DYS range have social issues, some don't. Different kids are different. Some do fine, others have a lot of trouble fitting in. The chance of the latter gets higher the farther you go from the mean.
It definitely sounds as though your child is gifted, but (as has been said before) he is very young, You would be most likely to get the best, most reliable results if you wait until he is 6 or 7 before testing. You know what he is like and will see quickly how he fits in in school to know if he needs more. It's likely scores will be lower with the WISC-V and it isn't clear yet how that will affect you. If you rush to have him tested with the SB-V, realize that it's quite different and that he may not necessarily get a similar score. The scores are highly correlated, but the tests are designed differently and some children do a little better on one or the other based on their particular strengths (even though the scores are usually similar unless there is a problem like a child who is distracted). The WISC is sometimes not recommended for gifted kids because of the emphasis on processing speed, but that isn't an issue if you can use the GAI instead.
I can't comment on Linda Silverman's work on learning styles because I haven't read it and am completely unfamiliar. I have heard many good things about her advice, so I don't want to discourage you at all. Is this school specifically using her approach, though? I do know that there are many claims made about learning styles that are not supported by empirical evidence. This doesn't necessarily mean they aren't true, but just that there isn't current data to support them. Let me be very clear, though, that I'm not talking about Linda Silverman's work because I'm not familiar with it. My point is that you need to make sure you know exactly what the school is offering to know whether it is likely to be good; just saying that they support different learning styles doesn't mean much. I think most gifted kids wouldn't do well with a lot of rote learning that could become repetitive, not just those with visual-spatial strengths. You need to know how exactly they work with kids with different learning styles and whether it is based on a specific approach (like you mention for Linda Silverman) that you can research in advance and ask others about (and, again, I've heard nothing but good things about her work - but the school may be using a completely different approach to learning styles).
We have had a lot of experience with schools trying to find the right educational environment and my experience is that it is never what you expect based on what they tell you in advance. They want you to choose their school. If you can let you child visit for a few hours or at least observe a little then that may help. If you can't, think over your biggest concerns and diplomatically ask how they handle those issues. Leaving it open ended rather than asking for a specific thing will give you a better idea of how they work. One principal took me to a classroom and just asked a teacher my question so I could hear her unprepared answer; that was fantastic not only because the answer was good but because it showed their confidence that everyone would work with us (and it turned out to be a wonderful school as well). Talk with teachers, not just administrators or admissions officers. Ask if they will let you talk with parents. The single most important thing is flexibility because you don't really know how your child will do in their school until he starts there. You need people who will work with you to come up with good solutions.
You mentioned seeing information from a psychologist who tested kids with two different tests, so I think you mean Deborah Ruf's work. It is very likely that kids will get lower scores on the new tests because that is what generally happens (just look at what happened when the last round of new tests came out). She is using two different tests, though, not older and newer versions of the same test. She is comparing the WPPSI-IV to the SB-V. So it's harder to draw conclusions because the tests are not only different in age, but also different in design.
Anyway, it sounds like your son had very promising scores and like being prepared to work with his school is important. I think you would get much more value out of waiting a little to get a new IQ test, though.
