@slingsrat I'm afraid you simply don't know what you're talking about. It kind of seems like you're confusing dual channel with double data rate (DDR). All DDR memory transmits data on both rising and falling edges of the clock. So 1066 MHz memory clock corresponds to 2133 MHz effective transfer rate (occasionally you'll see this made more explicit by using MT/s for effective speed rather than MHz). It is the effective transfer rate that is almost always used when describing RAM speed, so when someone says 3000 MHz RAM they mean 3000 MHz effective transfer rate.
All of that is completely independent and unrelated to the number of memory channels.
Here are numerous single stick kits that run at 3000+ MHz.
https://www.newegg.com/Product/ProductList.aspx?Submit=ENE&IsNodeId=1&N=100007611%20601190328%20600006067%20600006074%20600082361%20600561668%20600561669%20601203949%20601203950
@bmockeg I believe the 16 + 4 GB setup would sort of run in partial dual channel, by way of Intel's flex memory technology. But yeah, I think I'd personally just go with the single stick.