Whoa, we have many similarities. I also have a DS, age 6, who has a really low coding score, but other scores at the ceiling of the test. He also has an HG, uniformly gifted older sister. We are also in the thick of it, so I don't know if I have any great advice to share, but here is what I have so far.
DS had a WPPSI at age four with some surprisingly low scores (although not as low as yours). The psych we saw recommended having him evaluated by an OT and she diagnosed dyspraxia and fine motor issues. We did therapy for about a year, which did seem to help in many ways, but DS still has serious writing issues.
This year we had DS evaluated again and got score similar to yours. Some of the PRI and VRI scores were at the ceiling of the test, working memory was good but not gifted and processing speed, especially coding..... ouch.
The psych we worked with, someone who specializes in 2e, thought all his scores were somewhat suppressed due to the fact that DS was unwilling to really exert himself on many of the tasks, but functionally it was the best he was capable of at this time. In other words, he was capable of better, but refused to do it. She diagnosed ADHD and suspects dyslexia. She thinks that the fine motor problems contributed to the low coding score and that he might also have a visual problem, maybe convergence insufficiency. Our next step is to confirm or deny the visual problem with an evaluation by a developmental optometrist.
Here is where I am at with the placement issue. I believe that my son is gifted and also learning disabled. That means that although he has output issues, he has all the social and emotional needs of the gifted and will benefit from an academic placement that acknowledges those needs. If he was a child of average intelligence, there is no question that he would be in a regular classroom with his intellectual peers and also receiving special services for his areas of weakness. Because my son is gifted, I see no problem with him being in a gifted classroom with his intellectual peers receiving special services for his areas of weakness. The problem is getting the school to see it that way!
I guess a lot depends on the type of gifted programing offered in your area, too. If gifted services are mostly extra work sheets, then it may not be beneficial to your son. If they are offering more complex material and the opportunity to socialize with other gifted children, it might be worthwhile to pursue.
Good luck! Post if you find out anything new. It might be helpful to us since we are in a similar situation.
