Synthetic dreadlocks do not have the same look or feel as real hair dreads. Synthetic dreads are made out of plastic. Although we have never worked with human hair one could probably make some fairly accurate conclusions about the differences between working with human hair and synthetic hair:
Kanekalon synthetic dreadlocks are more durable than real hair dreads. We have found there our synthetic dreads (we only use dreads made from Kanekalon) don't really ever fall apart. Yes, that is because of how well we make them. Nonetheless, I have a feeling that non-living (not attached to the scalp, but cut and re-attached) real hair dreads would never be as durable as synthetic dreadlocks and would begin to break apart after regular wear and washing. Note: Sophie washes her hair regularly regardless of whether or not the dreads are in. The myth that you can't wash your hair with dreads is just that... a myth.
Mixing synthetic dreadlocks with real hair dreadlocks in the same wig will probably not work as well as using only synthetic dreads or only real hair dread.
The look of real hair dreads and synthetic dreads are not the same because the materials used to create the dread wig are not the same.
It is important to choose to use only synthetic dreads or real hair dreads (specifically refers to dead - or cut - real hair) for a wig as the consistency and look of the real vs synthetic dreads is quite different. That being said, mixing real dreads still on your head (living hair) with synthetic dreadlocks seems to work fine. Perhaps there is a shine and vitality to living hair that is lost once the hair is no longer living and attached to the scalp?