CeCe Moore reported on her blog the first comparison I have seen between 23andMe’s v3 and v4 chips.
It has been a concern over how 23andMe’s v4 chip would compare. The company admitted the new chip was looking at fewer SNPs than the old chip: 600,000 – 700,000 SNPs for v4 vs. 967,000 SNPs for v3.
Here’s the November 23andMe blog announcement for the new chip http://blog.23andme.com/news/23andmes-new-custom-chip They downplayed the major reduction in SNPs for the v4 chip. How can they expect a testing reduction of roughly 30 – 40% not be a major downgrade? It is too early to tell how the imputed values will work.
There are some good points on the portability of the v4 chip to Family Tree DNA (FTDNA) and GEDmatch. Hopefully the v4 chip will be compatible with FTDNA and GEDmatch.