The older DSM1 Spektrum receivers work great with the React. Just gotta make sure you have a new enough firmware version that will allow DSM to work with it. I've run at least 3 separate Pro and regular Spektrum RXs with no issues
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz