Like any after market product it's only as good as the information provided by the original manufacturer as to the architecture & technical approach used in a product.

Is DSM / DSM2 / DSMX proprietary? Is the technology protected by patents? Is there a published Rx interface that will allow any manufacturer to create and sell their own variant that is fully compatible with all of Spektrum's Tx? Did Spektrum teach others everything that others know about DSSS but not everything that Spektrum knows?

Just wondering ...

Bottom line - risk reward.